Electrical Energy and Power - Jamb Physics Past Questions and Answers

Question 31:

• JAMB 2002

A transistor is used in the amplification of signals because it

A. Controls the flow of current
B. Consumes a lot of power
C. Allows doping
D. Contains electron and hole carriers

Question 32:

• JAMB 2002

The carbon-granules microphone works on the principle of change in

A. Inductance
B. Resistance
C. Capacitance
D. Voltage

Question 33:

• JAMB 2003

In the diagram above, if each of the resistors can dissipate a maximum of 18W without becoming excessively heated, what is the maximum power the circuit can dissipate?

A. 27W
B. 18W
C. 9W
D. 5W

Question 34:

• JAMB 2004

Electrical appliances at home are normally earthed so that

A. The appliances are maintained at a lower p.d than the earth
B. Both the a.c and d.c sources can be used
C. A person touching the appliances is safe from electric shock
D. The appliances are maintained at a higher p.d than the earth

Question 35:

• JAMB 2005

A transformer is rated 240v. If the primary coil is 4000 turns and the secondary voltage 12v, determine the number of turns in the secondary coil.

A. 200
B. 100
C. 250
D. 150