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

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

Correct Answer:

Option C – 33.3%

Explanation

Internal resistance determines the maximum current that can be supplied

Efficiency = r/R × 100

= 2/6 × 100

= 33.3%