Current Electricity - Jamb Physics Past Questions and Answers

Question 21:

• JAMB 1981

The effect of closing the key K in the circuit shown above would be to

A. Increase the current by 0.6A
B. Reduce the current by 0.6A
C. Increase the current by 0.4A
D. Keep the current unchanged

Question 22:

• JAMB 1982

An electric iron is rated at 1000watts, 250v. The corresponding maximum resistance and accompanying current is

A. 62.5A, 4.0\(\Omega\)
B. 16.0A, 62.5\(\Omega\)
C. 62.5A, 16.0\(\Omega\)
D. 4.0A, 62.5\(\Omega\)
E. 4.0A, 250\(\Omega\)

Question 23:

• JAMB 1982

In copper plating, a current of 0.5A is allowed for cathode area of 100cm². If this current is maintained constant for 100 minutes, the thickness of the copper deposited will be approximately (the electrochemical equivalent of copper = 0.0003g/^oC, density of copper = 10^-4g/cm³ )

A. 10^-2mm
B. 10^-3mm
C. 10^-4mm
D. 10^-5mm
E. 10^-6mm

Question 24:

• JAMB 1982

A high-resistance voltmeter reads 3.0V when connected across the terminals of a battery on open circuit and 2.6V when the battery supplies a current of 0.2A through a lamp. The resistance of lamp is

A. 2.00\(\Omega\)
B. 13.00\(\Omega\)
C. 0.52\(\Omega\)
D. 0.13\(\Omega\)
E. 1.50\(\Omega\)

Question 25:

• JAMB 1982

what is the resultant resistance in the circuit given above

A. 11Ω
B. 8Ω
C. 4Ω
D. 3.6Ω
E. 4.3Ω