Question

The potential difference across the terminals of a battery is $50\, V$ when $11\,A$ current is drawn and $60 \,V$ when $1 \,A$ current is drawn. The emf and the internal resistance of the battery are

• A. $ 62\,V,\,2\,\Omega $
• B. $ 63\,V,\,{1}\,\Omega $
• C. $ 61\,V,\,{ 1}\,\Omega $
• D. $ 64\,V,2\,\Omega $

Answer 1

Answer: (C)

For a closed circuit, cell supplies a constant current in the circuit.

Equation of cell $E=V+I r$
For $V=50$ volt
$E=50+11\, r\,\,\,...(i)$
Similarly for $V=60$ volt
$E=60+r\,\,\,...(ii)$
From Eqs. (i) and (ii), we get
$r=1\, \Omega$
Substiruting the value of $r$ in $Eq$ (i), we get
$E=61\, V$