SPSC Lecturer Physics Past Papers

An electric field exerts a torque on a dipole only if?

1. The field is parallel to the dipole moment
2. The field is negative
3. The field is perpendicular to the dipole moment
4. The field is positive

When N-type semiconductor is heated?

1. Number of electrons increases while that of holes decreases
2. Number of holes increases while that of electrons decreases
3. Number of electrons and holes remain same
4. Number of electron and holes increases equally

Two charges are placed a certain distance apart in air. When a dielectric sheet is placed between them, the electrostatic force between them will?

1. Decrease
2. Increase
3. Remain unchanged
4. Become zero

Which of the these is the best description of a zener diode?

1. It operates in reverse region
2. It is a constant voltage device
3. It is a constant current device
4. All of these

What is required in a fusion reactor, in order to over come the electrostatic repulsive force between nuclides?

1. Very high pressure
2. Very high temperature
3. Very small volume
4. All of these

The period of the Physical Pendulum is?

1. T = 2π√1/Mgd
2. T = 2π √1/x
3. T = √4^1/MgR
4. All of these

Over-damping results in?

1. Slower return to equilibrium
2. Faster return to equilibrium
3. Equilibrium is never achieved
4. Unrhythmic to equilibrium

Two spheres of same material have radii r1 and r2. They are heated to same temperature and kept in same enclosure at low temperature. Their rates of loss of heat are in the ratio?

1. r1/r2
2. r2/r1
3. (r1/r2)^2
4. (r2/r1)^2

Which of the following statement is wrong?

1. Rough surfaces are better radiators than smooth surfaces
2. Highly polished mirror surfaces are very good radiators
3. Black surfaces are better absorbs that white ones
4. Black surfaces are better radiators then white ones

If the temperature of the sun is doubled, the rate of energy received on the earth will be increased by a factor of?

1. 2
2. 4
3. 8
4. 16