PYQ NEET- Current Electricity L-8

Question: A cell of emf $4 \mathrm{~V}$ and internal resistance $0.5 \Omega$ is connected to a $7.5 \Omega$ external resistance. The terminal potential difference of the cell is: (2022)#

A) $0.375 \mathrm{~V}$

B) $3.75 \mathrm{~V}$

C) $4.25 \mathrm{~V}$

D) $4 \mathrm{~V}$

Answer: $3.75 \mathrm{~V}$#

Explanation#

From Kirchhoff’s loop law :

$ V-I r-I R=0$

$\Rightarrow I=\left(\frac{V}{r+R}\right)$

Terminal potential difference across cell,

$ V_{A B}=I $

$V_{A B}=\frac{R V}{r+R}$

$=\frac{7.5 \times 4}{0.5+7.5}=3.75 \mathrm{~V}$