McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 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. |
|
Done Studing? Take A Test.
Great job completing your study session! Now it's time to put your knowledge to the test. Challenge yourself, see how much you've learned, and identify areas for improvement. Don’t worry, this is all part of the journey to mastery. Ready for the next step? Take a quiz to solidify what you've just studied.