Waec Physics 2019 Past Questions and Answers

Question 56:

• WAEC 2019

Explain each of the following terms as used in Electronics.
(a) free electrons;
(b) holes.

Question 57:

• WAEC 2019

(a) State the principle of operation of fibre optics.
(b) State two applications of fibre optics in medicine.

Question 58:

• WAEC 2019

(a) Define diffusion
(b) State two factors that affect the rate of diffusion

Question 59:

• WAEC 2019

(a) (i) State Newton’s Law of Universal Gravitation.
(ii) Define gravitational field.
(b) (i) Derive the equation relating the universal gravitational constant, G, and the acceleration of free fall, g, at the surface of the earth from Newton’s law of universal gravitation.
(ii) State two assumptions for which the relationship in 8(b)(i) holds.

(c) Calculate the force of attraction between a star of mass 2.00 x 1030 kg and the earth assuming the star is located 1.50 x 108 km from the earth. [Mass of the earth = 5.98 x 1024kg; G = 6.67 x 10-11N m\(^{2}\) kg-2; g = 10 m s\(^{-2}\)

(d) (i) Define escape velocity.
(ii) State two differences between the acceleration of free fall (g) and the universal gravitational constant (G).

Question 60:

• WAEC 2019

(a) (i) Explain latent heat.
(ii) State two factors that affect the rate of evaporation of a liquid

(b) Explain each of the following observations:
(i) On a dry day, water in a clay pot is cooler than water in a closed plastic container;
(ii) Food gets cooked faster in a pressure cooker than in an ordinary cooking pot.

(c) State two effects of heat on a substance.

(d) A 40 V electric heater is used to supply a current of 12 A for 1400 s to a body of mass 1.5 kg at the melting point of the body. The body melts and its temperature rises through 60\(^o\)C in an extra 72 s. Determine the:
(i) latent heat of fusion of the body;
(ii)specific heat capacity of the body.