Which of the following statements is the correct reason for using soft iron in making the armature or an electric bell?

• A. It is a diamagnetic material
• B. It loses its magnetism readily
• C. It is not easily magnetized
• D. It retains its magnetism for a long time

A converging lens of focal length 15cm forms a virtual image at a point 10cm from the lens. Calculate the distance of the object from the lens

• A. 10.00cm
• B. 6.00cm
• C. 5.00cm
• D. 1.50cm

The relative density of a liquid is the ratio of the

• A. Mass of water to the mass of an equal volume of liquid
• B. Upthrust in the liquid to the upthrust in water
• C. Density of water to the density of the liquid
• D. Upthrust in water to the upthrust in the liquid

What happens when three coplanar non-parallel forces are in equilibrium?

• A. Their lines of action are parallel.
• B. They are represented in magnitude only
• C. They are represented in direction only
• D. Their lines of action meet at a point

A band of 500 rectangular loops of wire of area 20 cm by 20 cm, encloses a region of magnetic field which charges from 1.0T to 0.4T within 5 seconds, calculate the induced e.m.f.

• A) 5.60 v
• B) 24.00 v
• C) 0.24 v
• D) 2.40 v

The most appropriate value of fuse for a kettle rated 220 V, 1.06 kW is

• A. 3A
• B. 6A
• C. 5A
• D. 4A

(a) Define:

(i) reactance;

(ii) impedance in an a.c.

The diagram here illustrates an a.c. generator. When the coil is rotated, an e.m.f is induced in the coil.

(i) Explain why an e.m.f. is induced.

(ii) State the purpose of the slip-rings.

(iii) Name and state the law used to determine the direction of the induced current.

(iv) State two ways to increase the induced e.m.f.

(c) A lamp is rated 12 V. 6 W. Calculate the amount of energy transformed by the lamp in 5 minutes.

A tennis ball projected at an angle 0 attains a range R = 78. If the velocity imparted to the ball by the racket is 30 ms\(^{-1}\), calculate O. [ g = 10 ms\(^{-2}\)]

Particles of mass 10^^-2kg is fixed to the tip of a fan blade which rotates with angular velocity of 100rad-1. If the radius of the blade is 0.2m, the centripetal force is

• A. 2 N
• B. 20 N
• C. 200 N
• D. 400 N

When a charge moves through an electric circuit in the direction of an electric force, it

• A. gains both potential and kinetic energy
• B. gains potential energy and lose kinetic energy
• C. loses potential energy and gains kinetic energy
• D. loses both potential and kinetic energy