(a) Electromagnetic Induction - Jamb Physics Past Questions and Answers

Question 6:

• JAMB 1981

A transformer has 300 turns of wire in the primary coil and 30 turns in the secondary coil.If the input voltage is 100 volts, the output voltage is

A. 5 volts
B. 10 volts
C. 15 volts
D. 20 volts
E. 25 volts

Question 7:

• JAMB 1981

A closed coil of wire is placed near a magnet. The magnet lies along the axis of the coil. Under which of the following conditions would there be no current in the coil?

A. When the coil is moved toward the stationary magnet
B. When the coil is moved away from the stationary magnet
C. When the coil is held stationary but the magnet is moved towards the coil
D. When both the coil and the magnet are held stationary
E. When the coil is held stationary but the magnet is moved away from the cell

Question 8:

• JAMB 1985

On which of the following does the operation of a moving coil ammeter depend? i. Electromagnetic induction ii. Force on a carrying-current conductor iii. Magnetic effect of an electric current

A. I only
B. Ii only
C. Iii only
D. Ii and iii only
E. I,ii and iii

Question 9:

• JAMB 1985

A transformer has a primary coil with 500 turns and a secondary coil with 2500 turns. When the voltage input to the primary coil is 120V, the output is

A. 6000V
B. 600V
C. 240V
D. 60V
E. 24V

Question 10:

• JAMB 1986

Which of the following is NOT a part of a d.c. electric motor?

A. Field-magnet
B. Armature
C. Commutator
D. Transformer