Test Index

JAMB Physics 2024 Paper

© africaexams.com

Question : 39

Total: 125

A cell of internal resistance of 2

\Omega

supplies current through a resistor, X if the efficiency of the cell is 75%, find the value of X.

2 $\Omega$
4 $\Omega$
6 $\Omega$
8 $\Omega$

Solution:

The efficiency of a cell = $\frac{\text{Ext. R}}{\text{Ext.R + int. r}}$ x 100

Ext. R = X

int. r = 2 $\Omega$

Efficiency = 75% = 0.75

0.75 = $\frac{\text{X}}{\text{X} + 2}$

0.75( X + 2 ) = X

0.75x + 1.5 = X

0.25X = 1.5

X = $\frac{1.5}{0.25}$ = 6 $\Omega$

© africaexams.com

Go to Question:

Prev Question

Next Question