The potential difference between the terminals of a cell in open circuit is 2.2 volt. With resistance of 5 ohm across the terminals of a cell, the terminal difference is 1.8 volt. The internal resistance of the cell is

Options

A. `(9)/(10)` ohm
B. `(10)/(9)` ohm
C. `(7)/(12)` ohm
D. `(12)/(7)` ohm

Answer

B

Explanation

`E=2.2` volt, `R=5Omega,V=1.8` volt
`therefore I=(V)/(R)=(1.8)/(5)=0.36A`
Fall in potential `=2.2-1.8=0.4` volt. `thereforeI_(T)=0.4`
`r=(0.4)/(0.36)=(10)/(9)` ohm.