1. Sound travels at the fastest speed in
a) steel
b) water
c) air
d) vacuum
Explanation: Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. In fact, sound waves travel over 17 times faster through steel than through air.
2. Oil raise up the wick in a lamp. The principle involves
a) the diffusion of oil through the wick
b) the liquid state of oil
c) capillary action phenomenon
d) volatility of oil
Explanation: The raise of oil up the wick in a lamp is an example of capillary action where adhesive forces are greater than cohesive forces.
3. Superconductors are substances which
a) conduct electricity at low temperature
b) offer high resistance to the flow of current
c) offer no resistance to the flow of electricity
d) conduct electricity at high temperatures
Explanation: By definition, superconductors are substances which display zero electrical resistance when a current is supplied, and are able to propagate such a current in a circuit indefinitely.
4. Light travels at the fastest speed in:
a) glass
b) water
c) hydrogen
d) vacuum
Explanation: Light travels at the fastest speed in Vacuum.
5.Railway tracks are banked on curves
a) necessary centrifugal force may be obtained from the horizontal component weight of the train
b) to avoid frictional force between the tracks and wheels
c) necessary centripetal force may be obtained from the horizontal component of the weight of the train
d) the train may not fly off in the opposite direction
Explanation: When a fast moving train takes a curved path, it tends to move away tangentially off the track. In order to prevent this, the curved tracks are banked on the outside to produce the necessary centripetal force required to keep the train moving in a curved path.
6. Out of the following pairs, choose the pair in which the physical quantities do not have identical dimension?
a) Pressure and Young's modules
b) Planck's constant and Angular momentum
c) Impulse and moment of force
d) Force and rate of change of linear momentum
Explanation:
Impulse and moment of force.
7.If two bodies of different masses, initially at rest, are acted upon by the same force for the same time, then the both bodies acquire the same:
a) Velocity
b) Momentum
c) Acceleration
d) Kinetic energy
Explanation: Since the Force and the duration of time for which it acted are same, the product of force and time will be the same for both. Since Force×time gives change in momentum of a body, and they had 0 momentum initially, their final momenta will be same.
8. Pick out the scalar quantity
a) Force
b) Pressure
c) Velocity
d) Acceleration
Explanation: Pressure is a scalar quantity.
9. Rectifiers are used to convert:
a) Direct current to Alternating current
b) Alternating current to Direct current
c) High voltage to low voltage
d) Low voltage to high voltage
Explanation: A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it "straightens" the direction of current.
10. Out of the following, which is not emitted by radioactive substance?
a) Electrons
b) Electromagnetic radiations
c) Alpha particles
d) Neutrons
Explanation: Out of the following neutrons is not emitted by radioactive substance.