McqMate
Chapters
| 101. |
Permittivity is expressed in |
| A. | Farad/sq-m |
| B. | Farad/metre |
| C. | Weber/metre |
| D. | Weber/sq-m |
| Answer» B. Farad/metre | |
| 102. |
Dielectric strength of a material depends on |
| A. | moisture content |
| B. | temperature |
| C. | thickness |
| D. | all of the above |
| Answer» D. all of the above | |
| 103. |
What will happen to an insulating medium if voltage more than the breakdown voltage is applied on it ? |
| A. | It will become magnetic |
| B. | It will melt |
| C. | It will get punctured or cracked |
| D. | Its molecular structure will get changed |
| Answer» C. It will get punctured or cracked | |
| 104. |
Which medium has the least dielectric strength ? |
| A. | Paraffin wax |
| B. | Quartz |
| C. | Glass |
| D. | Air |
| Answer» D. Air | |
| 105. |
1 volt/metre is same as |
| A. | 1 metre/coulomb |
| B. | 1 newton metre |
| C. | 1 newton/metre |
| D. | 1 joule/coulomb |
| Answer» C. 1 newton/metre | |
| 106. |
One volt is the same as |
| A. | one joule/coulomb |
| B. | one coulomb/joule |
| C. | one coulomb |
| D. | one joule |
| Answer» A. one joule/coulomb | |
| 107. |
The capacitance between two plates increases with |
| A. | shorter plate area and higher ap¬plied voltage |
| B. | shorter plate area and shorter dis¬tance between them |
| C. | larger plate area, longer distance between plates and higher,applied voltage |
| D. | larger plate area and shorter distance between plates |
| Answer» D. larger plate area and shorter distance between plates | |
| 108. |
The capacitance C is charged through a resistance R. The time constant of the charging circuit is given by |
| A. | CIR |
| B. | 1/RC |
| C. | RC |
| D. | RIC |
| Answer» C. RC | |
| 109. |
The bridge used for the measurement of the value of the capacitance is |
| A. | Wien's bridge |
| B. | Wheatstone bridge |
| C. | Schering bridge |
| D. | Hay's bridge |
| Answer» C. Schering bridge | |
| 110. |
If an ohmmeter reading immediately goes practically to zero and stays there, capacitor is |
| A. | charged |
| B. | short-circuited |
| C. | lossy |
| D. | satisfactory |
| Answer» B. short-circuited | |
| 111. |
Out of the following capacitors of identical rating which one will have the smallest dimensions ? |
| A. | Aluminium foil capacitor |
| B. | Mica capacitor |
| C. | Ceramic capacitor |
| D. | Paper capacitor |
| Answer» C. Ceramic capacitor | |
| 112. |
An uncharged conductor is placed near a charged conductor, then |
| A. | the uncharged conductor gets charged by conduction |
| B. | the uncharged conductor gets charged by induction and then attracted towards the charging body |
| C. | the uncharged conductor is attracted first and then charged by induction |
| D. | it remains as such |
| Answer» B. the uncharged conductor gets charged by induction and then attracted towards the charging body | |
| 113. |
The presence of an uncharged conductor near a charged one increases the |
| A. | charge of the charged conductor |
| B. | capacity of the charged conductor |
| C. | potential of the charged conductor |
| D. | all of the above |
| Answer» B. capacity of the charged conductor | |
| 114. |
Paper condenser is |
| A. | always polarised |
| B. | usually of fixed value |
| C. | electrolytic condenser |
| D. | a variable condenser |
| Answer» B. usually of fixed value | |
| 115. |
Mica capacitors are characterised by all of thte following except |
| A. | stable operation |
| B. | accurate value |
| C. | low leakage reactance |
| D. | low losses |
| Answer» C. low leakage reactance | |
| 116. |
A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of electric field is |
| A. | 100 kV/m |
| B. | 10 kV/m |
| C. | 5 kV/m |
| D. | 2 kV/m |
| Answer» A. 100 kV/m | |
| 117. |
For a good 0.05 uF capacitor ohmmeter reading should |
| A. | show low resistance momentarily and back off to a very high resis¬tance |
| B. | show high resistance momentarily and then a very low resistance |
| C. | go quickly to 50 ohm approximately and remain there |
| D. | not move at all |
| Answer» A. show low resistance momentarily and back off to a very high resis¬tance | |
| 118. |
The ohmmeter reading for a short circuited capacitor is |
| A. | infinity |
| B. | few kilo ohms |
| C. | few megaahms |
| D. | zero |
| Answer» D. zero | |
| 119. |
Which of the following statements is correct ? |
| A. | Mica capacitors are available in capacitance values of 5 to 20 \iF |
| B. | Air capapitors have a black band to indicate the outside foil |
| C. | Electrolytic capacitors must be connected in correct polarity |
| D. | Ceramic capacitors must be con¬nected in correct polarity |
| Answer» C. Electrolytic capacitors must be connected in correct polarity | |
| 120. |
Which of the following capacitors preferred for high frequency circuits ? |
| A. | Air capacitor |
| B. | Electrolytic capacitor |
| C. | Mica capacitor |
| D. | none of the above |
| Answer» C. Mica capacitor | |
| 121. |
An electrolytic capacitor is generally made to provide |
| A. | low capacitance |
| B. | fixed capacitance |
| C. | variable capacitance |
| D. | large value of capacitance |
| Answer» D. large value of capacitance | |
| 122. |
In order to remove static electricity from machinery |
| A. | construct insulated cabins |
| B. | insulate the machinery |
| C. | ground the framework |
| D. | humidify the surroundings |
| Answer» C. ground the framework | |
| 123. |
If a third equal and similar charge is placed between two equal and similar charges, then this third charge will |
| A. | move out of the field of influence of the two charges |
| B. | remain in stable equilibrium |
| C. | not be in equilibrium |
| D. | be in unstable equilibrium |
| Answer» B. remain in stable equilibrium | |
| 124. |
A region around a stationary electric charge has |
| A. | an electric field |
| B. | a magnetic field |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» A. an electric field | |
| 125. |
The minimum value of potential gradient in a cable occurs in |
| A. | insulation |
| B. | conductor |
| C. | outer sheath |
| D. | uniformly all over |
| Answer» A. insulation | |
| 126. |
Dielectric strength of medium |
| A. | increases with rise in temperature |
| B. | increases with moisture content |
| C. | is same for all insulating materials |
| D. | none of the above |
| Answer» D. none of the above | |
| 127. |
Acharge which when placed in vacuum from an equal and similar charge repels with a force of 9 x 10 N, is known as |
| A. | milli-coulomb |
| B. | micro-coulomb |
| C. | pico-coulomb |
| D. | coulomb |
| Answer» B. micro-coulomb | |
| 128. |
Dielectric strength of a medium is usually expressed in |
| A. | J/mm |
| B. | C/m2 |
| C. | kV/mm |
| D. | N/mm |
| Answer» C. kV/mm | |
| 129. |
A positive and a negative charge are initially 50 mm apart. When they are moved close together so that they are now only 10 mm apart, the force between them will be |
| A. | 5 times smaller than before |
| B. | 5 times greater than before |
| C. | 10 times greater than before |
| D. | 25 times larger than before |
| Answer» D. 25 times larger than before | |
| 130. |
Which is the most superior dielectric out of the following ? |
| A. | Air |
| B. | Glass |
| C. | Bakelite |
| D. | Paper |
| Answer» C. Bakelite | |
| 131. |
When a dielectric is placed in an electric field the field strength |
| A. | decreases |
| B. | increases |
| C. | reduces to zero |
| D. | remain unchanged |
| Answer» A. decreases | |
| 132. |
To prevent the generation of static charges on rubber or flat leather |
| A. | surface is moistened |
| B. | conductive dressing is done |
| C. | oil compound dressing is done |
| D. | talcum powder is sprayed on the surface |
| Answer» B. conductive dressing is done | |
| 133. |
Which of the following capacitor is preferred in case of single phase motor ? |
| A. | Mica capacitor |
| B. | Paper capacitor |
| C. | Electrolytic capacitor |
| D. | Ceramic capacitor |
| Answer» C. Electrolytic capacitor | |
| 134. |
A capacitance is a circuit component that opposes the change in circuit |
| A. | current |
| B. | voltage |
| C. | impedance |
| D. | none of the above |
| Answer» B. voltage | |
| 135. |
A condenser suitable for D.C. only is |
| A. | metallic plate variable gang condenser |
| B. | metallic paper capacitor |
| C. | oil impregrated paper condenser |
| D. | poled aluminium electrolytic condenser |
| Answer» D. poled aluminium electrolytic condenser | |
| 136. |
In a capacitor, the electric charge is stored in |
| A. | metal plates |
| B. | dielectric |
| C. | dielectric as well as metal plates |
| D. | none of the above |
| Answer» B. dielectric | |
| 137. |
Tesla is a unit of |
| A. | field strength |
| B. | inductance |
| C. | flux density |
| D. | flux |
| Answer» C. flux density | |
| 138. |
A permeable substance is one |
| A. | which is a good conductor |
| B. | which is a bad conductor |
| C. | which is a strong magnet |
| D. | through which the magnetic lines of force can pass very easily |
| Answer» D. through which the magnetic lines of force can pass very easily | |
| 139. |
The materials having low retentivity are suitable for making |
| A. | weak magnets |
| B. | temporary magnets |
| C. | permanent magnets |
| D. | none of the above |
| Answer» B. temporary magnets | |
| 140. |
A magnetic field exists around |
| A. | iron |
| B. | copper |
| C. | aluminium |
| D. | moving charges |
| Answer» D. moving charges | |
| 141. |
Ferrites are materials. |
| A. | paramagnetic |
| B. | diamagnetic |
| C. | ferromagnetic |
| D. | none of the above |
| Answer» C. ferromagnetic | |
| 142. |
Air gap has_______eluctance as compared to iron or steel path |
| A. | little |
| B. | lower |
| C. | higher |
| D. | zero |
| Answer» B. lower | |
| 143. |
The direction of magnetic lines of force is |
| A. | from south pole to north pole |
| B. | from north pole to south pole |
| C. | from one end of the magnet to another |
| D. | none of the above |
| Answer» B. from north pole to south pole | |
| 144. |
Which of the following is a vector quantity ? |
| A. | Relative permeability |
| B. | Magnetic field intensity |
| C. | Flux density |
| D. | Magnetic potential |
| Answer» B. Magnetic field intensity | |
| 145. |
The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is |
| A. | proportional to 7 |
| B. | proportional to X |
| C. | proportional to distance between the conductors |
| D. | inversely proportional to I |
| Answer» B. proportional to X | |
| 146. |
A material which is slightly repelled by a magnetic field is known as |
| A. | ferromagnetic material |
| B. | diamagnetic material |
| C. | paramag>etic material |
| D. | conducting material |
| Answer» B. diamagnetic material | |
| 147. |
When an iron piece is placed in a magnetic field |
| A. | the magnetic lines of force will bend away from their usual paths in order to go away from the piece |
| B. | the magnetic lines of force will bend away from their usual paths in order to pass through the piece |
| C. | the magnetic field will not be affected |
| D. | the iron piece will break |
| Answer» B. the magnetic lines of force will bend away from their usual paths in order to pass through the piece | |
| 148. |
Fleming's left hand rule is used to find |
| A. | direction of magnetic field due to current carrying conductor |
| B. | direction of flux in a solenoid |
| C. | direction of force on a current car¬rying conductor in a magnetic field |
| D. | polarity of a magnetic pole |
| Answer» C. direction of force on a current car¬rying conductor in a magnetic field | |
| 149. |
The ratio of intensity of magnetisation to the magnetisation force is known as |
| A. | flux density |
| B. | susceptibility |
| C. | relative permeability |
| D. | none of the above |
| Answer» B. susceptibility | |
| 150. |
Magnetising steel is normals difficult because |
| A. | it corrodes easily |
| B. | it has high permeability |
| C. | it has high specific gravity |
| D. | it has low permeability |
| Answer» D. it has low permeability | |
| 151. |
The left hand rule correlates to |
| A. | current, induced e.m.f. and direc¬tion of force on a conductor |
| B. | magnetic field, electric field and direction of force on a conductor |
| C. | self induction, mutual induction and direction of force on a conductor |
| D. | current, magnetic field and direc¬tion of force on a conductor |
| Answer» D. current, magnetic field and direc¬tion of force on a conductor | |
| 152. |
The unit of relative permeability is |
| A. | henry/metre |
| B. | henry |
| C. | henry/sq. m |
| D. | it is dimensionless |
| Answer» D. it is dimensionless | |
| 153. |
A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be |
| A. | zero |
| B. | BLI |
| C. | B2LI |
| D. | BLI2 |
| Answer» A. zero | |
| 154. |
The force between two long parallel conductors is inversely proportional to |
| A. | radius of conductors |
| B. | current in one conductor |
| C. | product of current in two conduc¬tors |
| D. | distance between the conductors |
| Answer» D. distance between the conductors | |
| 155. |
Materials subjected to rapid reversal of magnetism should have |
| A. | large area oiB-H loop |
| B. | high permeability and low hysteresis loss |
| C. | high co-ercivity and high reten-tivity |
| D. | high co-ercivity and low density |
| Answer» B. high permeability and low hysteresis loss | |
| 156. |
Indicate which of the following material does not retain magnetism permanently. |
| A. | Soft iron |
| B. | Stainless steel |
| C. | Hardened steel |
| D. | None of the above |
| Answer» A. Soft iron | |
| 157. |
The main constituent of permalloy is |
| A. | cobalt |
| B. | chromium |
| C. | nickel |
| D. | tungsten |
| Answer» C. nickel | |
| 158. |
The use of permanent magnets is. not made in |
| A. | magnetoes |
| B. | energy meters |
| C. | transformers |
| D. | loud-speakers |
| Answer» C. transformers | |
| 159. |
Paramagnetic materials have relative permeability |
| A. | slightly less than uuity |
| B. | equal to unity |
| C. | slightly more than unity |
| D. | equal to that ferromagnetic mate rials |
| Answer» C. slightly more than unity | |
| 160. |
Substances which have permeability less than the permeability of free space are known as |
| A. | ferromagnetic |
| B. | paramagnetic |
| C. | diamagnetic |
| D. | bipolar |
| Answer» C. diamagnetic | |
| 161. |
Two infinitely long parallel conductors in vacuum anf' separated 1 metre between centres >rhen a current of 1 ampere flows thn. ugh each conductor, produce on each otLer a force of |
| A. | 2 x 1(T2 N/m) |
| B. | 2 x KT3 N/m |
| C. | 2 x 10"5 N/m |
| D. | 2x 1(T7 N/m) |
| Answer» D. 2x 1(T7 N/m) | |
| 162. |
In the left hand rule, forefinger always represents |
| A. | voltage |
| B. | current |
| C. | magnetic field |
| D. | direction of force on the conductor |
| Answer» C. magnetic field | |
| 163. |
Which of the following is a ferromagnetic material ? |
| A. | Tungsten |
| B. | Aluminium |
| C. | Copper |
| D. | Nickel |
| Answer» D. Nickel | |
| 164. |
Ferrites are a sub-group of |
| A. | non-magnetic materials |
| B. | ferro-magnetic materials |
| C. | paramagnetic materials |
| D. | ferri-magnetic materials |
| Answer» D. ferri-magnetic materials | |
| 165. |
Gilbert is a unit of |
| A. | electromotive force |
| B. | magnetomotive force |
| C. | conductance |
| D. | permittivity |
| Answer» B. magnetomotive force | |
| 166. |
The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields |
| A. | meter is surrounded by strong magnetic fields |
| B. | a soft iron shielding is used |
| C. | a plastic shielding is provided |
| D. | a shielding of anon-magnetic material is used |
| Answer» B. a soft iron shielding is used | |
| 167. |
Reciprocal of permeability is |
| A. | reluctivity |
| B. | susceptibility |
| C. | permittivity |
| D. | conductance |
| Answer» A. reluctivity | |
| 168. |
The relative permeability is less than unity is case of |
| A. | ferromagnetic materials |
| B. | ferrites |
| C. | non-ferrous materials |
| D. | diamagnetic materials |
| Answer» D. diamagnetic materials | |
| 169. |
Which of the following is the unit of magnetic flux density ? |
| A. | weber |
| B. | lumens |
| C. | tesla |
| D. | none of the above |
| Answer» C. tesla | |
| 170. |
The magnetism left in the iron after exciting field has been removed is known as |
| A. | permeance |
| B. | residual magnetism |
| C. | susceptance |
| D. | reluctance |
| Answer» B. residual magnetism | |
| 171. |
Which of the following is not a unit of flux? |
| A. | Maxwell |
| B. | Telsa |
| C. | Weber |
| D. | All of the above |
| Answer» B. Telsa | |
| 172. |
Which of the following is expected to have the maximum permeability ? |
| A. | Brass |
| B. | Copper |
| C. | Zinc |
| D. | Ebonite |
| Answer» D. Ebonite | |
| 173. |
One telsa is equal to |
| A. | 1 Wb/mm2 |
| B. | 1 Wb/m |
| C. | 1 Wb/m2 |
| D. | 1 mWb/m2 |
| Answer» C. 1 Wb/m2 | |
| 174. |
Out of the following statements, concerning an electric field, which statement is not true ? |
| A. | The electric intensity is a vector quantity |
| B. | The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point |
| C. | An electric field is defined as a point in space at which an electric charge would experienc* a force |
| D. | Unit field intensity in the exertion of a force of one newton on a charge of one coulomb |
| Answer» B. The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point | |
| 175. |
When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon |
| A. | resistance of the coil |
| B. | motion of the magnet |
| C. | number of turns of the coil |
| D. | pole strength of the magnet |
| Answer» A. resistance of the coil | |
| 176. |
One maxwell is equal to |
| A. | 10 webers |
| B. | 10 webers |
| C. | 10 webers |
| D. | 10 webers |
| Answer» D. 10 webers | |
| 177. |
When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the centre of the circle |
| A. | will be zero |
| B. | will be infinite |
| C. | will depend on the amount of e.m.f. applied |
| D. | will depend on the radius of the circle |
| Answer» D. will depend on the radius of the circle | |
| 178. |
Susceptibility is positive for |
| A. | non-magnetic substances |
| B. | diamagnetic substances |
| C. | ferromagnetic substances |
| D. | none of the above |
| Answer» C. ferromagnetic substances | |
| 179. |
Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per metre of length of each conductor will be |
| A. | 100 N |
| B. | 10 N |
| C. | 1 N |
| D. | 0.1 N |
| Answer» D. 0.1 N | |
| 180. |
A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be |
| A. | 240 N |
| B. | 24 N |
| C. | 2.4 N |
| D. | 0.24 N |
| Answer» C. 2.4 N | |
| 181. |
The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength ? |
| A. | 2500 AT/m |
| B. | 250 AT/m |
| C. | 25 AT/m |
| D. | 2.5 AT/m |
| Answer» B. 250 AT/m | |
| 182. |
What is the magnitude and the direction of force per 1.1m length of a pair of conductors of a direct current linecarrying 10 amperes and spaced 100 mm apart ? |
| A. | 22 x 10"8 N |
| B. | 22 x 10"7 N |
| C. | 22 x 10-6 N |
| D. | 22 x 10"5 N |
| Answer» D. 22 x 10"5 N | |
| 183. |
A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ? |
| A. | 63.38 N/Wb |
| B. | 633.8 N/Wb |
| C. | 6338 N/Wb |
| D. | 63380 N/Wb |
| Answer» C. 6338 N/Wb | |
| 184. |
The unit of flux is the same as that of |
| A. | reluctance |
| B. | resistance |
| C. | permeance |
| D. | pole strength |
| Answer» D. pole strength | |
| 185. |
Unit for quantity of electricity is |
| A. | ampere-hour |
| B. | watt |
| C. | joule |
| D. | coulomb |
| Answer» D. coulomb | |
| 186. |
The Biot-savart's law is a general modification of |
| A. | Kirchhoffs law |
| B. | Lenz's law |
| C. | Ampere's law |
| D. | Faraday's laws |
| Answer» C. Ampere's law | |
| 187. |
The most effective and quickest may of making a magnet from soft iron is by |
| A. | placing it inside a coil carrying current |
| B. | induction |
| C. | the use of permanent magnet |
| D. | rubbing with another magnet |
| Answer» A. placing it inside a coil carrying current | |
| 188. |
The commonly used material for shielding or screening magnetism is |
| A. | copper |
| B. | aluminium |
| C. | soft iron |
| D. | brass |
| Answer» C. soft iron | |
| 189. |
If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity |
| A. | less than that of disc but in opposite direction |
| B. | equal to that of disc and in the same direction |
| C. | equal to that of disc and in the opposite direction |
| D. | less than that of disc and in the same direction |
| Answer» D. less than that of disc and in the same direction | |
| 190. |
A permanent magnet |
| A. | attracts some substances and repels others |
| B. | attracts all paramagnetic substan¬ces and repels others |
| C. | attracts only ferromagnetic sub¬stances |
| D. | attracts ferromagnetic substances and repels all others |
| Answer» A. attracts some substances and repels others | |
| 191. |
The retentivity (a property) of material is useful for the construction of |
| A. | permanent magnets |
| B. | transformers |
| C. | non-magnetic substances |
| D. | electromagnets |
| Answer» A. permanent magnets | |
| 192. |
The relative permeability of materials is not constant. |
| A. | diamagnetic |
| B. | paramagnetic |
| C. | ferromagnetic |
| D. | insulating |
| Answer» C. ferromagnetic | |
| 193. |
The materials are a bit inferior conductors of magnetic flux than air. |
| A. | ferromagnetic |
| B. | paramagnetic |
| C. | diamagnetic |
| D. | dielectric |
| Answer» C. diamagnetic | |
| 194. |
Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials. |
| A. | circular |
| B. | triangular |
| C. | rectangular |
| D. | none of the above |
| Answer» C. rectangular | |
| 195. |
A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be |
| A. | M |
| B. | M/2 |
| C. | 2 M |
| D. | M/4 |
| Answer» B. M/2 | |
| 196. |
A keeper is used to |
| A. | change the direction of magnetic lines |
| B. | amplify flux |
| C. | restore lost flux |
| D. | provide a closed path for flux |
| Answer» D. provide a closed path for flux | |
| 197. |
Magnetic moment is a |
| A. | pole strength |
| B. | universal constant |
| C. | scalar quantity |
| D. | vector quantity |
| Answer» D. vector quantity | |
| 198. |
The change of cross-sectional area of conductor in magnetic field will affect |
| A. | reluctance of conductor |
| B. | resistance of conductor |
| C. | (a) and (b) b >th in the same way |
| D. | none of the above |
| Answer» C. (a) and (b) b >th in the same way | |
| 199. |
The uniform magnetic field is |
| A. | the field of a set of parallel conductors |
| B. | the field of a single conductor |
| C. | the field in which all lines of mag¬netic flux are parallel and equidis¬tant |
| D. | none of the above |
| Answer» C. the field in which all lines of mag¬netic flux are parallel and equidis¬tant | |
| 200. |
The magneto-motive force is |
| A. | the voltage across the two ends of exciting coil |
| B. | the flow of an electric current |
| C. | the sum of all currents embraced by one line of magnetic field |
| D. | the passage of magnetic field through an exciting coil |
| Answer» C. the sum of all currents embraced by one line of magnetic field | |
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