Current Electricity - Jamb Physics Past Questions and Answers

Question 81:

• JAMB 1999

In the circuit above, the ammeter reads a current of 5.0 A when R = 8Ω and reads 7.0A when R = 5Ω. The value of the unknown resistance X is

A. 10.0Ω
B. 7.5Ω
C. 5.0Ω
D. 2.5Ω

Question 82:

• JAMB 1999

In the diagram above, if the internal resistance of the cell is zero, the ration of the powers P₁ and P₂ dissipated by R₁ and R₂

A. ^R₂/_R[sub]1[/sub]
B. ^R₁/_R[sub]2[/sub]
C. ^R₁+R₂/_R[sub]1[/sub]
D. ^R₁+R₂/_R[sub]2[/sub]

Question 83:

• JAMB 2000

A radio is operated by eight cells each of e.m.f. 2.0V connected in series. If two of the cells are wrongly connected, the net e.m.f. of the radio is

A. 8V
B. 10V
C. 12V
D. 16V

Question 84:

• JAMB 2000

A cell of internal resistance 0.01Ω can be measured accurately using the

A. Ohm meter
B. Metre bridge
C. Potentiometer
D. Electroscope

Question 85:

• JAMB 2000

A cell of internal resistance 1Ω supplies current to an external resistor of 3Ω. The efficiency of the cell is

A. 25%
B. 33%
C. 50%
D. 75%