Current Electricity - Jamb Physics Past Questions and Answers

Question 46:

• JAMB 1987

When two parallel wires carry currents in opposite directions, the force on either wire is

A. Away from the other wire
B. Zero, because the currents cancel each other
C. Twice as much as when the currents are in the same direction
D. Towards the other wire

Question 47:

• JAMB 1987

In the above, a voltage V is applied across the terminals P and Q. The voltage across the 1 ohm resistor is

A. V/8
B. V/4
C. V/3
D. V/2

Question 48:

• JAMB 1988

A cell of internal resistance 2 ohms supplies current to a 6 ohms resistor. The efficiency of the cell is

A. 12.0%
B. 25.0%
C. 33.3%
D. 75.0%

Question 49:

• JAMB 1988

When a resistance R is across a cell, the voltage across the terminals of the cell is reduced to two-third of its normal value. The internal resistance of the cell is

A. \(\frac{2}{1}\)R
B. \(\frac{1}{2}\)R
C. \(\frac{3}{2}\)R
D. 5R

Question 50:

• JAMB 1988

In the circuit diagram above, the ammeter reads a current of 3A when R is 5 ohms and 6A when R is 6 ohms,the value of the unknown resistance X is

A. 1
B. 2
C. 3
D. 4