1210+ Physics Solved MCQs

1101.

A hydrogen balloon floats because of –

A. Air pressure decreases with decrease in height
B. Air pressure decreases with decrease in weight
C. Weight of the balloon is less than the weight of air displaced by it
D. The pressure inside the balloon is more than the pressure outside it
Answer» C. Weight of the balloon is less than the weight of air displaced by it
Explanation: A hydrogen atom is very light. Most of the air on earth is made up of nitrogen, oxygen, and carbon dioxide. All of these elements are heavier than hydrogen, so the balloon is pushed upwards. Hydrogen weighs 0.08988 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.
1102.

The term ‘equinox’ means –

A. The path which the Earth takes around the Sun
B. The axis of the Earth around which it rotates
C. When the day and night are of equal duration
D. The time when the Sun seems to be going round and round in the sky in the Arctic but does not go below the horizon
Answer» C. When the day and night are of equal duration
Explanation: The name "equinox" is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and dayhave approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens.
1103.

After long periods of use, a grey spot develops on the inside of a bulb. This is because –

A. the tungsten filament evaporates and collects there
B. the heat of the bulb scorches the glass at the top
C. dust inside the bulb condenses on the top
D. glass undergoes a change due to the heat
Answer» C. dust inside the bulb condenses on the top
Explanation: At high operating temperatures, tungsten evaporates from the filament and gradually forms a gray film on the inside of the bulb. The inert gas atoms collide with the evaporating tungsten, causing some of the tungsten atoms to return to the filament. Eventually, however, a thin spot develops in the filament. When this happens, the filament will break and the bulb fails.
1104.

The blue colour of water in the sea is due to –

A. absorption of other colours except blue by water molecules
B. scattering of blue light by water molecules
C. reflection of blue light by impurities in sea water
D. reflection of blue sky by sea water
Answer» A. absorption of other colours except blue by water molecules
Explanation: Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green wavelengths of sunlight are absorbed by water molecules in the ocean. The reason the ocean is blue is due to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
1105.

Why Earth is called the blue planet?

A. Because of two-thirds surface covered by water
B. Because of water laden clouds in the atmosphere
C. Because of pollution in the atmosphere
D. None of these
Answer» A. Because of two-thirds surface covered by water
Explanation: Earth is called the blue planet because two-thirds of its surface is covered by water.
1106.

The density of a gas is maximum at –

A. Low temperature, low pressure
B. Low temperature, high pressure
C. High temperature, low pressure
D. High temperature, high pressure
Answer» B. Low temperature, high pressure
Explanation: The density of gases depends upon the temperature. The higher the temperature, the more the molecules are spread out and the lower the density. The result is that warm gases rise and cool gases sink.
1107.

A person standing on a railway platform listens to the whistles of arriving and departing trains. The whistle heard is -

A. the same in both cases in all respects
B. of higher intensity when train arrives
C. of higher pitch when train arrives
D. of higher pitch when train departs
Answer» C. of higher pitch when train arrives
Explanation: 0
1108.

The cause for the Tsunami, as deduced by the seismologists, is –

A. Gravitational pull of the moon
B. Low pressure trough in the ocean
C. Deformation of sea floor and vertical displacement of water
D. Sudden change in the monsoon wind
Answer» C. Deformation of sea floor and vertical displacement of water
Explanation: Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Tsunami can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with the Earth's crustal deformation; when these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position.
1109.

Should cars have bumpers that collapse under impact?

A. Yes, since the offending car should get damaged and pay for the mistake
B. No, since it would be very expensive to get the car repaired
C. No, since the colliding car would then ram into the occupants and kill them
D. Yes, since they help to absorb the impact of a collision and keep the occupants safe
Answer» D. Yes, since they help to absorb the impact of a collision and keep the occupants safe
Explanation: In automobiles, a bumper is the front-most or rear-most part., ostensibly designed to allow the car to sustain an impact without damage to the vehicle's safety systems. They are not capable of reducing injury to vehicle occupants in high-speed impacts, but are increasingly being designed to mitigate injury to pedestrians struck by cars.
1110.

Light houses are places with powerful lights to :

A. guide and resolve traffic jams in crowded metrocities during nights.
B. guide and help large crowds at religious gathering during nights.
C. indicate to the incoming warships, the location of a harbour during night.
D. guide and warn the ships coming from different directions in the ocean.
Answer» D. guide and warn the ships coming from different directions in the ocean.
Explanation: A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and used as an aid to navigation for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, safe entries to harbors, and can also assist in aerial navigation.
1111.

A bird sitting on a high tension electric wire does not get electrocuted because –

A. it has high resistance
B. the body is earthed
C. it does not form a closed path for the flow of current
D. its feet are good insulators
Answer» C. it does not form a closed path for the flow of current
Explanation: Electricity travels from a place of high voltage to low voltage, just as water travels from high elevation to low elevation. A bird, or any living thing, that touches a wire (where electricity is moving from high voltage to low voltage) and also touches the ground (a place with no voltage) creates a path that allows the electricity to travel through that body and into the place with no voltage. When electricity travels through a body in this fashion, electrocution takes place, and the bird can die.
1112.

A vacuum cleaner works on the principle of pressure difference. On the moon it will –

A. work as efficiently as on the earth
B. not work at all
C. work with reduced efficiency
D. work with increased efficiency
Answer» B. not work at all
Explanation: Vacuum cleaners work by creating a lower pressure just inside the opening which touches the floor. By creating a low pressure inside the machine, higher air pressure in the room pushes its way into the vacuum cleaner, taking the dirt with it.
1113.

When a body is taken from earth to moon –

A. Mass changes but weight remains same
B. Weight changes but mass remains same
C. Both weight and mass change
D. Both weight and mass re-main same
Answer» B. Weight changes but mass remains same
Explanation: Mass is how much stuff we are made of, and it is the same whether we are on Earth, on the moon, on Mercury, or anywhere else one can think of. We are held on Earth by gravity. Gravity pulling on mass is our weight .
1114.

Superconductors are those elements –

A. Whose conductivity is intermediate between metals and insulators
B. Whose resistance falls almost to zero at very low temperature
C. Which conduct electricity only at super-high temperature
D. Which conduct electricity only, at super-high temperatures
Answer» B. Whose resistance falls almost to zero at very low temperature
Explanation: Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state.
1115.

Ail oil drop spreads over water because

A. oil is lighter than water
B. oil is more viscous
C. oil does not mix with water
D. surface tension of oil is much smaller than that of water
Answer» D. surface tension of oil is much smaller than that of water
Explanation: Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e.g. water striders) to run on the water surface. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids.
1116.

The nature of .fuse wire is –

A. high resistance and low melting point.
B. high resistance and high melting point.
C. low resistance and high melting point.
D. low resistance and low melting point.
Answer» A. high resistance and low melting point.
Explanation: A fuse or fusable link works by opening an electrical circuit when the current becomes too high. As the current increases, the temperature of the wire increases. So a fuse wire should have a low melting point and should beconnected in series with the appliance. Besides, it should have a comparatively high resistance.
1117.

In a railway track, two rails are joined end to end with a gap in between them because –

A. steel can be saved
B. accidents due to contraction in winter can be avoided
C. air-gaps are necessary for bearing the weight of running train
D. accidents due to expansion in summer can be avoided.
Answer» D. accidents due to expansion in summer can be avoided.
Explanation: The volume of materials changes depending on current temperature. Usually heat makes them expand, and cold leads them to contract. There have to be gaps to avoid strain on the tracks. The same applies in many other fields of engineering, i.e. bridge building.
1118.

When a pall of water is swung in a vertical circle, the water does not fall out at the top of the loop when the speed is –

A. below a certain minimum value irrespective of amour of water In the pail
B. above a certain minimum value irrespective of amount of water in the pail
C. above a certain minimum value depending on amount of water in the pail
D. below a certain minimum value depending on amount of water in the pail
Answer» B. above a certain minimum value irrespective of amount of water in the pail
Explanation: When a pail of water is swung in a vertical circle, the water does not fall out at the top of the loop when the speed is great enough. At every point in the circle the water tries to fall vertically out due to the force of gravity g but also tries to move in a straight line due to its circular motion.
1119.

Vehicle tyres are inflated properly –

A. to ensure smooth running.
B. to allow the vehicle to take more load.
C. to avoid skidding and to minimize friction
D. to go fast and save fuel.
Answer» C. to avoid skidding and to minimize friction
Explanation: Under-inflated tyres create more friction with the road, increasing fuel consumption by up to ten per cent and are prone to skidding on either wet or slippery surfaces. Low pressures also lead to premature wear and risk of tyre blowout or bulging.
1120.

Refrigeration is a process which –

A. kills bacteria
B. slows down the bacterial growth
C. Inactivates the bacteria
D. Plasmolyses the bacteria
Answer» B. slows down the bacterial growth
Explanation: Bacteria thrive in warm, moist conditions. Refrigeration allows the temperature to be lowered so far that food can be stored for days or even months. Keeping food cold (at or below 4°C) slows down bacterial growth which helps reduce the risk of food borne illness.
1121.

The function of ball bearings in a wheel is –

A. to increase friction
B. to convert kinetic friction into rolling friction
C. to convert static friction into kinetic friction
D. just for convenience
Answer» B. to convert kinetic friction into rolling friction
Explanation: A ball bearing is a type of rolling- element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads.
1122.

On a cold day when the room temperature is 15°C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15°C, because –

A. metals have higher thermal capacity than plastics
B. plastics have a lower density than metals
C. metals are good conductors of heat
D. plastics have a higher thermal conductivity than metals
Answer» C. metals are good conductors of heat
Explanation: On a chilly day, the room temperature is lower than our body temperature. Since metals have a higher coefficient of thermal conductivity than plastic, they are better conductor of heat than plastic. So, when we touch the metal cap and the plastic body of a pen, heat from our fingers will flow to the metal cap much more quickly than to the plastic body.
1123.

The apparent weight of a person in a lift which is moving down with uniform acceleration is               .

A. greater than the weight when the person is stationary
B. twice the weight when the person is stationary
C. less than the weight when the person is stationary
D. same as the weight when the person is stationary
Answer» C. less than the weight when the person is stationary
Explanation: 0
1124.

Air Quality Index is -

A. an air pollutant measuring machine
B. a measuring scale to show quality of air
C. used for measuring humidity level
D. used for forecasting rain
Answer» B. a measuring scale to show quality of air
Explanation: The AQI is an index for reporting daily air quality. It tells us how clean or polluted our air is, and what associated health effects might be a concern for us.
1125.

It is easy to burst a gas-filled balloon with a needle than with a nail. It is because –

A. nail is more longer than needle.
B. nail exerts more pressure than needle on the balloon.
C. needle exerts more pressure than nail on the balloon.
D. gas is reactive with the needle.
Answer» C. needle exerts more pressure than nail on the balloon.
Explanation: It is easy to burst a gas-filled balloon with a needle than with a nail because the needle applies more pressure than nail. Besides, the application of the pressure is on a small surface area than in the case of nail. In the case of needle, it is a very tiny area at the tip of the needle, so only a little force gives a lot of pressure (pressure = force/area).
1126.

For a body floating in water, the apparent weight is equal to -

A. Actual weight of the body
B. Zero
C. Weight of the body minus weight of the liquid
D. Weight of the body plus upward thrust
Answer» C. Weight of the body minus weight of the liquid
Explanation: 0
1127.

The characteristic invalid for heat radiation is that it travels –

A. in a straight line
B. in all directions
C. with the speed of light
D. heating the medium through which it passes
Answer» C. with the speed of light
Explanation: Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.
1128.

The method of magnetization is:

A. hammering a magnet
B. heating a magnet
C. passing direct current through it
D. passing alternating current through it
Answer» A. hammering a magnet
Explanation: Hammering a rod will either allow it to become slightly magnetic inlaid along a magnetic field (i.e.North - South) or demagnetize it if laid across the field lines (i.e. East-West). A current passing through a coil will produce a magnetic field.
1129.

Which among the following is false about work?

A. If displacement is zero, work is zero
B. Work done can be negative
C. It is a vector quantity
D. Its unit is Joule
Answer» C. It is a vector quantity
Explanation: Vector, in physics, a quantity that has both magnitude and direction. For example, displacement, velocity, and acceleration are vector quantities, while speed (the magnitude of velocity), time, and mass are scalars.
1130.

Which of the following is false?

A. Most carbon compounds are poor conductors of electricity.
B. The force of attraction between carbon molecules is not very strong.
C. The atomic number of carbon is 6.
D. The earth’s crust has about 2% carbon in the form of minerals.
Answer» D. The earth’s crust has about 2% carbon in the form of minerals.
Explanation: 0
1131.

Two vectors are said to be equal if –

A. only their magnitudes are same
B. only their directions are same
C. both magnitude and direction are same
D. magnitudes are same but directions are opposite
Answer» C. both magnitude and direction are same
Explanation: If the magnitude as well as direction of two vectors are equal, then they are known as equal vectors. In other words, two vectors are said to be equal, if they possess equal magnitude and are headed towards the same direction. For two equal vectors, their directed line segments must be parallel.
1132.

A real gas can act as an ideal gas in -

A. high pressure and low temperature
B. low pressure and high temperature
C. high pressure and high temperature
D. low pressure and low temperature
Answer» B. low pressure and high temperature
Explanation: Real gases approximate ideal gases when their pressure is relatively low, and their temperature reasonably high. A real gas deviates increasingly from ideality as it is compressed and cooled to near the point at which it will condense into a liquid.
1133.

The Dynamo converts –

A. Electrical Energy into Mechanical Energy
B. Mechanical Energy into Magnetic Energy
C. None of these
D. Mechanical Energy into Electrical Energy
Answer» D. Mechanical Energy into Electrical Energy
Explanation: Dynamo is a device for converting mechanical energy into electrical energy, especially one that produces direct current. It uses electromagnetic principles to convert mechanical rotation into a pulsing direct electric current through the use of a commutator.
1134.

Winch of the following is not true about X-rays?

A. have low penetrating power
B. travel with the speed of light
C. Can be reflected or refracted
D. can affect photographic plates
Answer» A. have low penetrating power
Explanation: X-rays and gamma rays are photons, i.e. high-energy light-waves. When emitted by a source, for example, radium or cobalt, located outside the body, they easily pass through the body, hence they are usually called penetrating radiation. Because X-rays are penetrating, they can be used in diagnostic medicine to image human bones or human organs made opaque by a dye.
1135.

A Fuse wire is characterized by –

A. High resistance and low melting point
B. High resistance and high melting point
C. Low resistance and high melting point
D. Low resistance and low melting point
Answer» D. Low resistance and low melting point
Explanation: A fuse is a type of low resistance resistor that acts as a sacrificial device to provide over current protection, of either the load or source circuit. Low resistance causes the fusewire to melt if a current more than the safe current for the appliance starts flowing through the circuit.
1136.

Ice is packed in saw dust because –

A. saw dust will not get melted easily.
B. saw dust is poor conductor of heat.
C. saw dust is a good conductor of heat.
D. saw dust does not stick to the ice.
Answer» B. saw dust is poor conductor of heat.
Explanation: ice needs to absorb heat energy to melt and become water (called latent heat of fusion). Since saw-dust is a poor conductor of heat, it takes more time for the ice to absorb the required heat energy. This allows ice to remain in solid state for more time when packed in saw dust.
1137.

A stone is dropped from the roof of a house towards the ground. The kinetic energy of the stone will be maximum:

A. just after it is dropped
B. when it is just on the half-way
C. just before it touches the ground
D. when it touches the ground
Answer» C. just before it touches the ground
Explanation: When an object reaches the ground it has its maximum value of kinetic energy just before touching the ground. Since kinetic energy + potential energy= Constant; so on reaching ground the potential energy of an object becomes zero (0). The kinetic energy on reaching ground becomes maximum.
1138.

What is Hooke’s Law?

A. Stress is inversely proportional to strain.
B. Stress is directly proportional to strain.
C. Stress and strain are dependent on each other.
D. Stress and strain are independent of each other.
Answer» B. Stress is directly proportional to strain.
Explanation: Hooke’s law is a principle of physics that states that the force (F) needed to extend or compress a spring by some distance X scales linearly with respect to that distance.
1139.

Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of-

A. Convection only
B. Conduction and convection only
C. Radiation and convection only
D. Convection, conduction and radiation
Answer» C. Radiation and convection only
Explanation: Conduction is the transfer of heat energy by direct contact, convection is the movement of heat by actual motion of matter; radiation is the transfer of energy with the help of electromagnetic waves.
1140.

A drop of liquid assumes spherical shape because:

A. Intermolecular forces are strong in liquids
B. A sphere has the least surface area for a given volume
C. A sphere has the largest surface area for a given volume
D. Inter molecular forces are weak in liquids
Answer» B. A sphere has the least surface area for a given volume
Explanation: A drop of liquid assumes spherical shape because a sphere has the least surface area for a given volume.
1141.

What are audible sound waves?

A. Having frequency less than 20 Hz
B. Having frequency between 20 Hz to 20000 Hz
C. Having frequency more than 20000 Hz
D. None of above
Answer» B. Having frequency between 20 Hz to 20000 Hz
Explanation: 0
1142.

Sun appears red in colour at sun-rise and sunset due to –

A. the fact that sun emits only red colour at that time
B. red light having longer wave length scatters away
C. that sun Comes out of the mountains
D. that all other colours scatter away except red
Answer» D. that all other colours scatter away except red
Explanation: According to Rayleigh's law, the intensity of scattered light varies inversely as the fourth power of its wavelength. Sunlight consists of seven colours. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon.
1143.

Why does a cannon recoil after firing?

A. Conservation of energy
B. Backward thrust of gases produced
C. NeMon's third law of motion
D. Newton's first law of motion
Answer» C. NeMon's third law of motion
Explanation: Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gases (ejecta), According to Newton's third law. In case of canons, the momentum is transferred to the ground through its mount.
1144.

During the motion of a projectile fired from the earth surface,             .

A. its kinetic energy remains constant
B. its momentum remains constant
C. vertical component of its velocity remains constant
D. horizontal component of its velocity remains constant
Answer» D. horizontal component of its velocity remains constant
Explanation: The motion of a projectile is a two-dimensional motion—Horizontal motionand vertical motion—that take place independent of each other. The horizontal velocity of a projectile is constant (a never changing in value). The force of gravity continuously affects the vertical component, so the vertical motion is a uniformly accelerated motion.
1145.

A system exhibiting S.H.M. must possess –

A. Elasticity as well as inertia
B. Elasticity, inertia and an external force
C. Elasticity only
D. Inertia only
Answer» A. Elasticity as well as inertia
Explanation: Basic conditions to execute simple harmonic motion are: (i) There must be an elastic restoring force acting on the system, (ii) the system must have inertia, and (iii) the acceleration of the system should be directly proportional to its displacement and is always directed to mean position.
1146.

The ringing of an electric bell in an enclosed evacuated glass bell jar is not heard outside because -

A. the ringing is not loud enough
B. the glass of the bell jar absorbs the sound waves
C. the bell jar is too small
D. there is no air or any other gas in the bell jar
Answer» D. there is no air or any other gas in the bell jar
Explanation: 0
1147.

At hill stations, the boiling point of water will be –

A. same as at sea level
B. less than that at sea level
C. more than that at sea level
D. equal to the melting point of ice
Answer» B. less than that at sea level
Explanation: The boiling point is the temperature at which the vapour pressure of theliquid equals the environmental pressure surrounding the liquid. Atmospheric pressure is due to air above any given point. The atmospheric pressure at high altitudes like hill station is less than at the sea level.
1148.

Indicate the correct arrangement for electromagnetic radiation in order of their increasing wavelength.

A. Microwave, infrared, visible. X-rays
B. X-rays, visible, infrared, microwave
C. Visible, infrared, microwave, X-rays
D. X-rays, infrared, visible, microwave
Answer» D. X-rays, infrared, visible, microwave
Explanation: The Electromagnetic spectrum in order of decreasing energy, thus increasing wavelength : Gamma Rays-wavelength: 0.01 nm; X-rays -1 nm ; Ultra-violet Rays-0.1 micrometres ; Visible Light-Red light : 0.7 micrometres, Violet Light : 0.4 micrometres ; Infrared Radiation-0.01 mm ; Microwaves -less than 10 cm, usually lem ; Radiowaves- Long, Medium and Short Waves : 1am-10 m ; and Very High Frequency (VHF) and Ultra High Frequency (UHF): 10 m-10 cm.
1149.

A black body can absorb radiations of

A. lower wavelengths only
B. intermediate wavelengths only
C. higher wavelengths only
D. all wavelengths
Answer» D. all wavelengths
Explanation: A black body is a theoretical object that absorbs 100% of the radiation that hits it. Therefore it reflects no radiation and appears perfectly black. At a particular temperature the black body would emit the maximum amount of energy possible for that temperature. This value is known as the black body radiation. It would emit at every wavelength of light as it must be able to absorb every wavelength to be sure of absorbing all incoming radiation.
1150.

The water from a hand pump is warm in winter because –

A. Our body is cold in winter and the water appears to be warm
B. The temperature inside the earth is higher than the atmospheric temperature
C. The pumping process causes friction which warms up the water
D. Inside water comes out and absorbs heat from the environment
Answer» B. The temperature inside the earth is higher than the atmospheric temperature
Explanation: In winter, the outside temperature is lower than that of water flowing out of the pump, and therefore, the water is warm. Whereas in summer, the outside temperature is higher than the water of the pump, and therefore, it feels cold.
1151.

When hot liquid is poured into a thick glass tumbler, it cracks because glass –

A. is a bad conductor of heat so only inner surface expands
B. has high temperature coefficient of expansion
C. has a very low specific heat
D. has low temperature coefficient of expansion
Answer» A. is a bad conductor of heat so only inner surface expands
Explanation: When hot liquid is poured into a thick glass tumbler, it cracks because glass is abad conductor of heat so only inner surface expands.
1152.

Hydro-electric power is a:

A. non-renewable natural resource
B. a mixture of renewable and non-renewable natural resource
C. neither renewable nor non renewable resource
D. renewable natural resource
Answer» D. renewable natural resource
Explanation: Hydro-electric power is a renewable natural resource.
1153.

The electric motor converts -

A. Electrical energy into mechanical energy
B. Mechanical energy into electrical energy
C. Electrical energy into light energy
D. None of these
Answer» A. Electrical energy into mechanical energy
Explanation: A generator converts mechanical energy into electrical energy, while a motor does the opposite - it converts electrical energy into mechanical energy.
1154.

Burns caused by steam are much severe than those caused by boiling water because –

A. Steam pierces through the pores of body quickly
B. Steam has latent heat
C. Steam is gas and engulfs the body quickly
D. Temperature of steam is higher
Answer» B. Steam has latent heat
Explanation: When water changes into steam, it absorbs latent heat, and when steam condenses to form water, it gives out an equal amount of latent heat. Bums caused by steam are much more severe than those caused by boiling water, simply because steam contains more heat (in the form of latent heat) than boiling water.
1155.

According to special theory of relativity the mass of a particle –

A. increases with increase in velocity with respect to an observer.
B. decreases with increase in velocity.
C. decreases with decrease in velocity.
D. is independent of its velocity.
Answer» A. increases with increase in velocity with respect to an observer.
Explanation: According to the Special Theory of Relativity, the mass of a moving object measures more as its velocity increases until, at the speed of light, it becomes infinite. This is because as an object gains speed, it gains more (kinetic) energy.
1156.

Vegetables are cooked in lesser time by adding a pinch of salt while cooking because

A. boiling point of water increases
B. latent heat of vaporization of water decreases
C. latent heat of vaporization of water increases
D. boiling point of water decreases
Answer» A. boiling point of water increases
Explanation: Adding salt raises the boiling point of water, which allows food to cook at higher temperature. The higher the temperature, the higher the rate of heat transfer between the food and water, thus it cooks more quickly.
1157.

A man standing at the top of a tower has two spheres A and B. He drops sphere A downwards and throws sphere B horizontally at the same time. Which of the following is correct?

A. Both the spheres will reach the ground simultaneously.
B. A will reach the ground first.
C. B will reach the ground first.
D. The question is incomplete because the masses of the spheres are not given.
Answer» A. Both the spheres will reach the ground simultaneously.
Explanation: If no air resistance is present, the rate of descent depends only on how far the object has fallen, no matter how heavy the object is. This means that two objects will reach the ground at the same time if they are dropped simultaneously from the same height.
1158.

The wavelength at which the peak of intensity of blackbody radiation Occurs –

A. increases with increase in temperature
B. decreases with increase in temperature
C. is the same at all temperatures
D. does not follow any pattern as temperature changes
Answer» B. decreases with increase in temperature
Explanation: According to Wien's displacement law, when the temperature of a blackbody radiator increases, the overall radiated energy increases. Wavelength of maximum emission from a blackbody is inversely proportional to its temperature. Shorter-wavelength (higher-frequency) light corresponds to higherenergy photons.
1159.

A dynamo converts             .

A. Mechanical energy into sound energy
B. Mechanical energy into electrical energy
C. Electrical energy into mechanical energy
D. None of these
Answer» B. Mechanical energy into electrical energy
Explanation: The dynamo, by attaching it in between the two tires, converts the mechanical energy (which of course, is produced by paddling) into electrical energy, and by connecting the wires going out of the dynamo to light, it glows without any flaw.
1160.

If we want to calculate the pressure of a liquid at the bottom of a vessel, the quantity which is not required to determine it, is –

A. Height of the liquid column
B. Surface area of the bottom of the vessel
C. Density of the liquid
D. Acceleration due to gravity at the bottom of the vessel
Answer» B. Surface area of the bottom of the vessel
Explanation: The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity. Static fluid pressure does not depend on the shape, total mass, or surface area of the liquid.
1161.

What is the relation between wavelength, frequency and velocity?

A. velocity of wave = frequency * wavelength
B. velocity of wave = frequency/wavelength
C. velocity of wave = wavelength/frequency
D. None of above
Answer» A. velocity of wave = frequency * wavelength
Explanation: 0
1162.

Ozone layer in the outer atmosphere helps us in –

A. reflecting radio waves and makes radio communication possible
B. regulating he temperature of atmosphere
C. absorbing cosmic ray particles
D. absorbing U-V radiations
Answer» D. absorbing U-V radiations
Explanation: The ozone layer is a layer in Earth's atmosphere containing relatively high concentrations of ozone (03) which absorbs 97- 99% of the Sun's medium-frequency ultraviolet light.
1163.

Stationary wave is formed by –

A. a transverse wave superposing a longitudinal wave
B. two waves of the same speed superposing
C. two waves of same frequency travelling in the same direction
D. two waves of same frequency travelling in the opposite direction
Answer» D. two waves of same frequency travelling in the opposite direction
Explanation: Stationary or standing waves are formed in a medium when two waves having equal amplitude and frequency moving in opposite directions along the same line, interfere in a confined space. Generally, such waves are formed by the superposition of a forward wave and the reflected wave. Both longitudinal and transverse types of waves can form a stationary wave.
1164.

What is inertia?

A. Tendency to resist change in the current state
B. Tendency to impart acceleration to a body
C. Tendency to bring a body to rest
D. Tendency to change its current state
Answer» A. Tendency to resist change in the current state
Explanation: 0
1165.

A good conductor while carrying current is -

A. alternately charged positive and negative
B. negatively charged
C. positively charged
D. electrically neutral
Answer» B. negatively charged
Explanation: Electrons carry current in a good conductor of electricity and they are negatively charged. This makes a good electrical conductor negatively charged.
1166.

The propagation of sound waves in a gas involves –

A. Adiabatic compression and rarefaction
B. Isothermal compression and rarefaction
C. Isochoric compression and rarefaction
D. Isobaric compression and rarefaction
Answer» A. Adiabatic compression and rarefaction
Explanation: Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing. During propagation, waves can be reflected, refracted, or attenuated by the medium. Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves.
1167.

Which of the following events occurred first?

A. Albert Einstein propounded the General Theory of Relativity
B. Max Planck unveiled the Quantum Theory
C. Marconi first transmitted a wireless signal
D. Madame Marie Curie became the first woman Nobel Prize winner
Answer» B. Max Planck unveiled the Quantum Theory
Explanation: General Theory of Relativity: a theory of gravitation developed by Einstein in the years 1907-1915; Quantum Theory of Max Planck: 1900; Transmission of wireless signal by Marconi: first Atlantic wireless transmission on December 11, 1901; and Madame Curie becoming the first woman Nobel Prize winner.
1168.

Which of the following is not a property of heavy water?

A. Boiling point of heavy water is lower than that or ordinary water
B. Density of heavy water is higher than that of ordinary water
C. Freezing point of heavy water is higher than that of ordinary water
D. It produces corrosion
Answer» A. Boiling point of heavy water is lower than that or ordinary water
Explanation: Heavy water, formally called deuterium oxide or 2H90 or D20, is a form of water that contains the hydrogen isotope deuterium, rather than the common protium isotope. The colloquial term heavy water is often also used to refer a highly enriched water mixture that contains mostly deuterium oxide but also contains some ordinary water molecules as well: for instance heavy water used in CANDLE reactors is 99.75% enriched by hydrogen atom-fraction.
1169.

A mirage occurs because of –

A. Reflection by hot ground
B. Total internal reflection by layers of air
C. Interference of light
D. Diffraction of light
Answer» B. Total internal reflection by layers of air
Explanation: A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky. Mirages can be categorized as "inferior" (meaning lower), "superior" (meaning higher) and "Fata Morgana", one kind of superior mirage consisting of a series of unusually elaborate, vertically-stacked images, which form one rapidly-changing mirage. Cold air is denser than warm air and has therefore a greater refractive index.
1170.

Knot is a measure of –

A. The speed of ship
B. The curvature of spherical objects
C. Solar radiation
D. Intensity of earthquake shock
Answer» A. The speed of ship
Explanation: The knot (pronounced not) is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph. There is no standard abbreviation but km is commonly used. The knot is a non-SI unit accepted for use with the International System of Units (SI).
1171.

When the main switch of the house is put off it disconnects the –

A. live wire only
B. live wire and the earth wire
C. live wire and the neutral wire
D. earth wire and the neutral wire
Answer» C. live wire and the neutral wire
Explanation: Three wires enter most homes from the power pole—two "hot" wires and a third "neutral" wire. Each hot wire provides 120- volt current for conventional lights, receptacles, and appliances when paired with the neutral wire, which is normally kept at zero volts or "ground potential." When both, hot wires are used together with the neutral, they power large 240-volt appliances such as air conditioners and electric ovens. All the electric appliances stop working in a house when the main switch is put off because the electric circuit (the path where the electricity travels) gets opened.
1172.

Negative feedback in amplifiers –

A. increases bandwidth and decreases noise
B. decreases bandwidth and decreases noise
C. increases bandwidth and in-creases noise
D. decreases bandwidth and increases noise
Answer» A. increases bandwidth and decreases noise
Explanation: Voltage gain, input impedance, output impedance, bandwidth etc. are few important characteristics of an amplifier. These parameters are more or less constant for a given amplifier. Quite often, the values of these parameters are required to be controlled. This can be conveniently achieved by employing a technique, called the feedback.
1173.

What is Hooke's Law?

A. Stress is inversely proportional to strain.
B. Stress is directly proportional to strain.
C. Stress and strain are dependent on each other.
D. Stress and strain are independent of each other.
Answer» B. Stress is directly proportional to strain.
Explanation: Hooke's law is a principle of physics that states that the force (F) needed to extend or compress a spring by some distance X scales linearly with respect to that distance.
1174.

Wollen clothes keep the body warm because –

A. Wool increases the temperature of the body
B. Wool is a had conductor
C. Wool absorbs radiant heat from outer objects
D. Wool rejects heat from the outer objects
Answer» B. Wool is a had conductor
Explanation: It is just because woolen clothes have fibres and between those fibres air is trapped which reduces heat loss. Air reduces heat loss because it is an insulator or poor conductor of heat. Wool has seeral qualities that distinguish it from hair or fur: it is crimped, it is elastic, and it grows in staples (clusters) .Wool's scaling and crimp make it easier to spin the fleece by helping the individual fibers attach to each other, so they stay together. Because of the crimp, wool fabrics have a greater bulk than other textiles, and retain air, which causes the product to retain heat.
1175.

Flywheel is an important part of a steam engine because it -

A. gives strength to the engine
B. accelerates the speed of the engine
C. helps the engine in keeping the speed uniform
D. decreases the moment of Inertia
Answer» C. helps the engine in keeping the speed uniform
Explanation: 0
1176.

The bats can fly in the dark because –

A. They can see the objects in darkness
B. They have weak legs and are likely to be attacked by predators
C. They generate flashes of light
D. They generate ultrasonic sound waves
Answer» C. They generate flashes of light
Explanation: 0
1177.

A microscope used in pathological laboratories forms –

A. magnified, virtual, erect, Image
B. diminished, real and erect image
C. Magnified, virtual and inverted image
D. Diminished, virtual and erect image
Answer» C. Magnified, virtual and inverted image
Explanation: A microscope is an instrument that produces a clear magnified image of an object viewed through it. A basic microscope is made up of two converging lenses. The first lens creates a real image which serves as the object for the second lens, and the image created by the second lens is the one a viewer sees. The final image is virtual and is inverted compared to the original object.
1178.

It is dangerous to observe solar eclipse with naked eyes because –

A. Infrared radiations from sun burn our retina
B. Ultraviolet radiations from Sun burn our retina
C. All radiations from sun initiate chemical reactions in eyes
D. Cosmic rays reach eyes more during the eclipse
Answer» B. Ultraviolet radiations from Sun burn our retina
Explanation: The solar radiation that reaches the surface of Earth ranges from ultraviolet (UV) radiation at wavelengths longer than 290 nm to radio waves in the meter range. The tissues in the eye transmit a substantial part of the radiation between 380 and 1400 nm to the light-sensitive retina at the back of the eye. The concern over improper viewing of the Sun during an eclipse is for the development of "eclipse blindness" or retinal burns.
1179.

The wall of a dam is broader at the base

A. because streamlining is required
B. to withstand pressure that increases with depth
C. to withstand pressure that increases in a horizontal plane
D. to withstand pressure that is increased with atmospheric pressure
Answer» B. to withstand pressure that increases with depth
Explanation: Darns are built broader at the base for two reasons. The first is because it needs to be stable enough to support the dam, and two, the bottom of the dam needs to be able to deal with the increased pressure of the water, as you get further down. Particular to dams, at the lower part of the structure the lower levels of water are at higher pressure than the upper levels of the water.
1180.

A transformer –

A. converts DC to AC
B. is used to decrease or increase AC voltage
C. converts AC voltage to D.C. voltage
D. converts electrical energy into mechanical energy
Answer» B. is used to decrease or increase AC voltage
Explanation: Transformers have made long- distance transmission of electric power a practical reality, as AC voltage can be "stepped up" and current "stepped down" for reduced wire resistance power losses along power lines connecting generating stations with loads. At either end (both the generator and at the loads), voltage levels are reduced by transformers for safer operation and less expensive equipment.
1181.

'Mirage' is an example of –

A. refraction of light only
B. total internal, reflection of light only
C. refraction and total internal reflection of light
D. dispersion of light only
Answer» C. refraction and total internal reflection of light
Explanation: A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky. In contrast to a hallucination, a mirage is a real optical phenomenon which can be captured on camera, since light rays actually are refracted to form the false image at the observer's location. As light passes from colder air across a sharp boundary to significantly warmer air, the light rays bend away from the direction of the temperature gradient.
1182.

The absolute zero is a temperature at which             .

A. molecular motion in a gas would cease
B. water freezes
C. all gases become liquid
D. all gases become solid
Answer» A. molecular motion in a gas would cease
Explanation: Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance.
1183.

Surface tension in a liquid is due to :

A. Adhesive force between molecules
B. Cohesive force between molecules
C. Gravitational force between molecules
D. Electrical force between molecules
Answer» B. Cohesive force between molecules
Explanation: Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviors of liquids.
1184.

When a vehicle passes, TV reception gets distorted. This is because –

A. metal reflects radiowaves
B. spark plug creates electromagnetic disturbances
C. vehicle pollution affects the performance of the TV components
D. modern vehicles use electro ignition system
Answer» B. spark plug creates electromagnetic disturbances
Explanation: This is caused due to the interference caused by the electromagnetic waves generated by a passing vehicle. These waves were within the same frequency range as that of the waves of TV reception and hence caused Interference. interference is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower amplitude.
1185.

The snow on the mountains does NOT melt all at once when it is heated by the sum because:

A. It becomes very hard
B. It reflects most of the heat from the sum
C. it has a low specific heat capacity
D. it has a high latent heat of fusion
Answer» B. It reflects most of the heat from the sum
Explanation: Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. And when snow does melt, it is not because of the sunlight. Snow does not melt on a spring day because of the sun's heat. It melts because of the warm air from the sea.
1186.

The water from a hand pump is warm in winter because -

A. our body is cold in winter and the water appears to be warm
B. the temperature inside the Earth is higher than the atmospheric temperature
C. the pumping process causes friction which warms up the water
D. inside water comes out and absorbs heat from the environment
Answer» B. the temperature inside the Earth is higher than the atmospheric temperature
Explanation: 0
1187.

‘Mirage' is an example of -

A. Refraction of light only
B. Total internal reflection of light only
C. Refraction and total internal reflection of light
D. Dispersion of light only
Answer» C. Refraction and total internal reflection of light
Explanation: 0
1188.

It is easier to carry two buckets of water in one hand each, than to carry only one in one hand because –

A. weights of buckets are balanced
B. centre of gravity falls within the body
C. centre of gravity and centre of equilibrium fall within the feet
D. resultant weight of buckets is zero
Answer» C. centre of gravity and centre of equilibrium fall within the feet
Explanation: When the buckets containing equal amount of water are held in both hands, weight is spaced out more evenly than it would be if one had to carry a single bucket. For balancing the weight, the centre of gravity and the centre of equilibrium should fall, in the present case, within the feet.
1189.

Dynamo is a device for converting –

A. Heat energy into electrical energy
B. Mechanical energy into electrical energy
C. Magnetic energy into electrical energy
D. Chemical energy into electrical energy
Answer» B. Mechanical energy into electrical energy
Explanation: A dynamo is a device for converting mechanical energy into electrical energy, esp. one that produces direct current. A dynamo is an electrical generator that produces direct current with the use of a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric- power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.
1190.

The magnifying power of an astronomical telescope can be decreased by –

A. decreasing the focal length of the eyepiece
B. increasing the focal length of the eyepiece
C. increasing the focal length of the objective
D. None of these
Answer» B. increasing the focal length of the eyepiece
Explanation: The magnifying power (M) of astronomical is given by M = (focal length ofobjective)/(focal length of eye piece). This expression shows that in order to obtain high magnification, focal length of object must be large and that of eye piece should be small. Similarly, for decreased magnification, focal length of eye piece should be increased.
1191.

Which of the following events occurred first?

A. Albert Einstein propounded the General Theory of Relativity
B. Max Planck unveiled the Quantum Theory
C. Marconi first transmitted a wireless signal
D. Madame Marie Curie be-came the first woman Nobel Prize winner
Answer» B. Max Planck unveiled the Quantum Theory
Explanation: General Theory of Relativity: a theory of gravitation developed by Einstein in the years 1907-1915; Quantum Theory of Max Planck: 1900; Transmission of wireless signal by Marconi: first Atlantic wireless transmission on December 11, 1901; and Madame Curie becoming the first woman Nobel Prize winner: shared her 1903 Nobel Prize in Physics with her husband Pierre Curie.
1192.

The velocity of sound in air –

A. decreases with increase of temperature
B. increases with decrease of temperature
C. does not depend on temperature
D. decreases with decrease of temperature
Answer» D. decreases with decrease of temperature
Explanation: Assuming air to be an ideal gas, the speed of sound c depends on temperature only, not on the pressure or density. As air temperature increases, so does the speed of sound and vice versa. This is due to the individual air particles having extra kinetic energy at higher temperatures and lesser at lower temperatures.
1193.

The sensation of weightlessness in a spacecraft in an orbit is due to the –

A. Absence of gravity outside
B. Acceleration in the orbit which is equal to the acceleration due to gravity outside
C. Presence of gravity outside but not inside the spacecraft
D. Fact that spacecraft in the orbit has no energy
Answer» B. Acceleration in the orbit which is equal to the acceleration due to gravity outside
Explanation: Weightlessness in space is caused by the simple physical factors that cause the limitation of gravity. While on Earth, external forces are pushing or pulling on a person's body, however when a spacecraft enters orbit, the people and objects aboard the craft enter a state of free fall. Essentially, the vehicle and all of its contents are falling towards the Earth causing the sensation of weightlessness similar to the state a person feels when enjoying the amusement park ride. Many people believe that a lack of gravity is the root cause for weightlessness in space.
1194.

Energy in reflected light :

A. does not depends on the angle of incidence
B. increases with the increase in angle
C. decreases with the increase in angle of incidence
D. becomes maximum for angle of incidence equal to 45°
Answer» B. increases with the increase in angle
Explanation: Reflected waves are simply those waves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter. The amount of incident-wave energy that is reflected from a surface depends on the nature of the surface and the angle at which the wave strikes the surface.
1195.

A person standing on a railway platform listens to the whistles of arriving and departing trains. The whistle heard is –

A. the same in both cases in all respects
B. of higher intensity when train arrives
C. of higher pitch when train arrives
D. of higher pitch when train departs
Answer» C. of higher pitch when train arrives
Explanation: Sound is a sequence of waves of pressure that propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation).
1196.

A dynamo is a device which –

A. creates mechanical energy
B. creates electrical energy
C. converts mechanical energy into electrical energy
D. converts electrical energy into mechanical energy
Answer» C. converts mechanical energy into electrical energy
Explanation: A dynamo is an electrical generator that produces direct current with the use of a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.
1197.

A piece of paper and a cricket ball are dropped from the same height. Under which of the following conditions do both reach the surface simultaneously?

A. They must have the same volume
B. They must have the same density
C. They must have the same mass
D. They must be dropped in vacuum
Answer» D. They must be dropped in vacuum
Explanation: When a piece of paper and a cricket ball are dropped from the same height, they reach the surface at different time because the shape of the paper is more flat and it behaves like a parachute causing more air resistance acting on it with respect to the ball. But, in order to reach the surface at the same time by both the
1198.

Woollen cloth protects the body from cold because –

A. it is a good conductor of heat
B. it is a poor conductor of heat
C. external heat rays enter into the body through the woollen cloth
D. it reflects heat
Answer» B. it is a poor conductor of heat
Explanation: It is just because woolen clothes have fibres and between those fibres air is trapped which reduces heat loss. It reduces heat loss because it is an insulator or poor conductor of heat.
1199.

The threshold frequency is the frequency below which -

A. photo current is constant
B. photo current increases with voltage
C. photo current decreases with volt
D. photo electric emission is not possible
Answer» D. photo electric emission is not possible
Explanation: 0
1200.

Oil rises up the wick in a lamp because

A. Oil is very light
B. Of the diffusion of oil through the wick
C. Of the surface tension phenomenon
D. Of the capillary action phenomenon
Answer» D. Of the capillary action phenomenon
Explanation: It is because of the capillary action phenomenon because of which oil rise up the wick in a lamp. Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube,in porous materials such as paper, in some nonporous materials such as liquefied carbon fiber, or in a cell.
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