### Physics Past Questions

4821

a. State one difference between an intrinsic and an extrinsic semiconductor.

b. Draw a circuit diagram to illustrate full wave smoothing rectification.

WAEC 2023
4822

a. What is fibre optics?

b. State two reasons why optical fibres are preferred to copper cables in the telecommunication industry.

WAEC 2023
4823

ai. State the reason why simple harmonic motion is periodic.

ii. State two factors that affect the period of oscillation of a simple pendulum.

iii. Sketch a graph of the total mechanical energy, E, against displacement, y, for the motion of a simple pendulum from one extreme position to the other.

b. The diagram above illustrates an oscillatory pendulum. Calculate the work done in raising the pendulum to point B, if the mass of the bob is 50 g.
[g = $$10 ms^2$$]

c. A spiral spring of spring constant, k, and natural length, l, has a scale pan of mass 0.04 kg hanging on its lower end while the upper end is firmly fixed to a support. When an object of mass 0.20 kg is placed on the scale pan, the length of the spring becomes 0.055 m and when the object is replaced with another object of mass 0.28 kg, the length of the spring becomes 0.065 m. Calculate the values of k and l.
[g = $$10 ms^2$$]

WAEC 2023
4824

a. Define each of the following terms used with simple machines:

b. A truck of mass 1.2 × $$10^3$$ kg is pulled from rest by a constant horizontal force of 25.2N on a leveled road. If the maximum speed attainable in the process is 60 km/h.
Calculate the: i. work done by the force; ii. distance traveled by the truck in reaching the maximum speed.

c. State two differences between absolute zero temperature and ice point.

d. An uncalibrated liquid-in-glass thermometer was used in determining a Celsius temperature. The readings are tabulated below

 Temperature/°C -6 0 100 Length of column/ cm L 2 15

WAEC 2023
4825

ai. Why are parabolic mirrors suitable for use in the headlamps of vehicles?

ii.  Draw a ray diagram to illustrate the answer in 10(a)(i).

bi. State two applications of echoes.

ii. An observer standing at a point, P, on the same horizontal ground as the foot, H, of a tower, shouts, and 1.20 s later, he hears the echo. He then moved to another point, Q, 40 m from P, and shouted again but the echo was heard after 1.45 s. Calculate the:
I. distance between P and H;
II. speed of sound in air.

ci. Define the term absolute refractive index of a medium.

ii. A piece of coin falls accidentally into a tank containing two immiscible liquids A and B as illustrated in Fig. 10.0 above.

Calculate the displacement of the coin when viewed vertically from above.
[refractive index of A = 1.3, refractive index of B = 1.4]

WAEC 2023