question_answer

The potential difference across the terminals of a battery is SO V when 11A 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)  63V, 1 \[\Omega \].

C)  61V, 1 \[\Omega \]      

D)  64V, 2 \[\Omega \]

Correct Answer: C

Solution :

 For a closed circuit, cell supplies a constant current in the circuit. Equation of cell \[E=V+Ir\] For \[V=50\,volt\] \[E=50+11r\]                ...(i) Similarly for V = 60 volt \[E=60+r\]                 ...(ii) From Eqs. (i) and (ii), we get \[r=1\,\Omega \] Substituting the value of r in Eq (i), we get \[E=61V.\]