Electromagnetic Induction - Jamb Physics Past Questions and Answers

Question 16:

• JAMB 2001

A transistor function mainly as a

A. Switch and amplifier
B. Rectifier and an amplifier
C. Charge storer and an amplifier
D. Charge storer and a switch

Question 17:

• JAMB 2006

The main purpose of the transformer in an a.c radio set is to?

A. Increase power to the radio
B. Step up the voltage
C. Convert energy from a.c to d.c
D. Step down the voltage

Question 18:

• JAMB 2007

Lenz's law is a law of conservation of

A. Electric charge
B. Electric current
C. Energy
D. Momentum

Question 19:

• JAMB 2008

The d.c generator has essentially the same components as the a.c generator except the presence of?

A. Slip-ring
B. Carbon brushes
C. Split ring
D. Armature

Question 20:

• JAMB 2008

A step-down transformer has a power output of 50 W and efficiency of 80%. if the mains supply voltage is 200 v, calculate the primary current of the transformer.

A. 0.31 A
B. 3.20 A
C. 3.40 A
D. 5.00 A