A cell of internal resistance of 2\(\Omega\) supplies current through a resistor, X if the...

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.

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\(\Omega\)

There is an explanation video available below.

Previous Next

{{ settings.no_comment_msg ? settings.no_comment_msg : 'There are no comments' }}