physics MCQs – Page 9

Practise multiple-choice questions from physics for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

physics Mcqs
161. A rubber cord of cross-sectional area 2cm2 has a length of 1m. When a tensile force of 10N is applied the length of the cord increases by 1cm. What is the youngs modulus of rubber ?
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A. 0.510-6 Nm-2

B. 0.210-6Nm-2

C. 5106 Nm-2

D. 2108 Nm-2

162. Which one is a unit vector ?
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A. ??3 i^ + ??3 j^ + ??3 k^

B. 1/??3 i^ + 1/??3 j^ +1/ ??3 k^

C. ??3 / 3 i^ + ??3 / 3 j^ + ??3 / 3 k^

D. Both B and C are correct
163. What are the dimensions of stress ?
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A. ML-T-1

B. MLT-2

C. ML-2T-1

D. ML-1T-2
164. Two vectors A and B are making angle ? with each other. The scalar projection of vector B on vector A is written as____________?
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A. A.B/A

B. A.B/B

C. A.cos?

D. Both a and b are correct

165. A choke is used as a resistance in_________________?
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A. DC circuit

B. AC circuits

C. Both AC and DC circuit

D. Full wave rectifier circuit

166. Unit vector n^ is along______________?
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A. X-axis

B. Y-axis

C. Z-axis

D. Normal on a surface
167. Electrons_________________?
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A. Can exist inside the nucleus

B. Cannot exist inside the nucleus

C. Can exist both inside and outside the nucleus

D. Do not know
168. The unit of radioactivity curie is equal to________________?
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A. 3.60 x 1010 disintegration per sec

B. 3.74 x 109 disintegration per sec

C. 3.55 x 1010 disintegration per sec

D. 3.70 x 1010 disintegration per sec
169. The unit vector in the direction of vector A = 2 i^ -2j^ + k^ is_______________?
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A. (2i^ 2j^ +k^)/9

B. (2i^ 2j^ +k^)/5

C. (2i^ 2j^ +k^)/3

D. 2i^ 2j^ + k^

170. The average power and instantaneous power become equal if work is done at __________________?
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A. any rate

B. at uniform rate

C. at high rate

D. at variable rate

171. If velocity is doubled then__________________?
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A. momentum increases 4 times and K.E increases 2 times

B. momentum increases 2 times and K.E increases 4 time

C. momentum increases 2 times and K.E increases constant

D. momentum and K.E. remain same

172. Nuclei having the same mass number but different atomic number are____________?
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A. Isotones

B. Isobars

C. Isotopes

D. Isomers

173. n instrument which can measure potential without drawing any current is_____________________?
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A. voltmeter

B. cathode ray oscilloscope (CRO)

C. galvanometer

D. ammeter

174. With increase in temperature the electrical conductivity of intrinsic semi conductor___________________?
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A. Increases

B. First increases then decreases

C. Decreases

D. Remains same

175. If one or more of the neutrons emitted during fission cab be used to build up further fission then the reaction is self-sustained and is known as __________________?
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A. Fission reaction

B. Fusion reaction

C. Chemical reaction

D. Chain reaction
176. Mass defect per nucleon is ___________________?
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A. The average energy of the nucleus

B. Packing fraction

C. The binding energy of the nucleus

D. All of above are one and the same thing

177. The dot product of force and velocity is__________________?
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A. torque

B. power

C. work

D. impulse

178. When the coil of the galvanometer is in equilibrium then the deflecting couple is____________________?
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A. smaller than the restoring couple

B. greater than the restoring couple

C. zero

D. equal to the restoring couple
179. What is the SI unit of modulus of elasticity of substance ?
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A. Being a number it has no unit.

B. Jm-2

C. Nm-2

D. Nm-1

180. When a force is parallel to the direction of motion of the body, then work done on the body is_____________________?
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A. maximum

B. minimum

C. zero

D. infinity