Electric power transmission - Jamb Physics Past Questions and Answers

Question 6:

• JAMB 1990

Electrical power is transmitted at a high voltage rather than low voltage because the amount of energy loss is reduced due to

A. Heat dissipation
B. Production of eddy currents
C. Excessive current discharge
D. Excessive voltage distance

Question 7:

• JAMB 1990

What precaution should a manufacturer take to ensure that energy loss in a transformer is minimized?

A. The winding of the transformer should be made of high resistance wire
B. The core should be made of thin sheets of metal
C. No magnetic material should be used to make the core
D. The flux linking the primary with the secondary coils should be minimum

Question 8:

• JAMB 1993

The primary aim in high tension transmission is to

A. Minimize electrical energy losses due to heat production
B. Increase the rate of energy transfer by using high voltage
C. Increase the current in the wire
D. Generate electricity at high current and low voltage

Question 9:

• JAMB 1995

If the maximum voltage across a 100ohms resistor is 20V, then the maximum power it can dissipate is

A. 5.00W
B. 4.00W
C. 2.00W
D. 25W

Question 10:

• JAMB 1995

The primary winding of a transformer has 400 turns and its secondary has 100 turns. If a source of e.m.f. of 12V is applied to the primary, the secondary e.m.f. will be

A. 3V
B. 6V
C. 24V
D. 48V