Waec Physics 2014 Past Questions and Answers

Question 56:

• WAEC 2014

(a) State two conditions under which photo-electrons can be emitted from the surface of a metal.
(b) List two particle characteristics of electromagnetic waves.

Question 57:

• WAEC 2014

(a) Give two examples each of:
(i) rotational motion;
(ii) linear motion.
(b) Describe a laboratory experiment to determine the density of an irregularly shaped solid.
(c) State Newton's second law of motion
(d) Explain the term inertia.
(e)

The diagram above illustrates a body of mass 5.0 kg being pulled by a horizontal force F. If the body accelerates at 2.0 ms\(^{-2}\) and experiences a frictional force of 5 N, calculate the:
(i) net force on it;
(ii) magnitude of F;
(iii) coefficient of kinetic friction. [ g = 10 ms\(^{-2}\)]

Question 58:

• WAEC 2014

a) Define heat capacity and state its unit.
(b) List two effects of heat on a substance.
(c) Explain how a tightly fitted glass stopper could be removed from a reagent bottle.
(d) A quantity of pepper soup of mass 800 g poured into a plastic container with a tight-fitting lid has a temperature of 30°C. The container is then placed in a microwave oven, rated 1200 W and operated for 3 minutes.
(i) Calculate the final temperature attained by the soup. (Assuming no heat losses).
(ii) Explain why containers with tight-fitting lids are not suitable for use in microwave cooking.
(iii) When the soup is brought out and allowed to cool, a dent is observed on the container. Explain. [Take specific heat capacity of the soup = 4000 Jkg\(^{-1}\) K\(^{-1}\)]

Question 59:

• WAEC 2014

(a) State the three characteristics of sound and the factor on which each of them depends.
(b) Explain resonance as applied to sound.
(c) What role does echo play in the construction of a concert hall?
(d) The surface of an ear drum (assumed circular) has a radius 2.1 mm. It resonates with an amplitude of 0.8 x 10\(^{-7}\) in as a result of impulses received from an external body vibrating at 2400 Hz. If the resulting pressure change on the ear drum is 3.6 x 10\(^{-5}\) NM\(^{-2}\), calculate the:
(i) period of oscillation;
(ii) velocity;
(iii) acceleration;
(iv) force. [\(\pi\) = 3.14 ].

Question 60:

• WAEC 2014

(a) Define electromotive force.
(b) State:
(i) the principle of operation of a potentiometer,
(ii) two advantages that a potentiometer has over a voltmeter in measuring potential difference.
(c)(i) Sketch and label a diagram of a gold-leaf electroscope.
(ii) Give one use of a gold-leaf electroscope.
(d)(i) Explain the action of a magnetic relay.
(ii) List two factors which determine the magnitude of an induced emf in a coil.
(iii) A current of 5 A passes through a straight wire in a uniform magnetic field of flux density 2.0 x10\(^{-3}\) T. Calculate the force per unit length exerted on the wire when it is inclined at 30° to the field.