Physics Past Questions and Answers

The number of holes in an intrinsic semiconductor

A Is not equal to the number of free electrons
B Is greater than the number of free electrons
C Is equal to the number of free electrons
D Is less than the number of free electrons

Question 42:

Name the type of equilibrium for each position of the ball

A A - unstable, B - neutral, C - stable
B A - stable, B - neutral, C - unstable
C A - stable, B - unstable, C - neutral
D A - unstable, B - stable, C - neutral

Question 43:

Rainbow formation is as a result of the combination of which of the following phenomena?
(i) Reflection
(ii) Dispersion
(iii) Total internal reflection
(iv) Refraction

A (ii) and (iv) only
B (i), (iii) and (iv) only
C (ii), (iii) and (iv) only
D (i), (ii) and (iv) only

Question 44:

The surface temperature of a swimming pool on a warm day is 25ºC and the temperature at the bottom is 15ºC. If the swimming pool has a surface area of 620 \(m^2\) and a depth of 1.5m. Find the rate at which energy is transferred by conduction from the surface to the bottom of the swimming pool.

[Thermal conductivity of water (k) = 0.6071 Wm-1K-1]

A 2.5kw
B 250kw
C 300kw
D 3.0kw

Question 45:

Which process is responsible for production of energy in stars?

A Nuclear reaction
B Nuclear fission
C Nuclear fusion
D Radioactive decay