Paragraph: A nichrome wire A B, 100 ~cm long and of uniform cross...

Paragraph: A nichrome wire $A B, 100 \mathrm{~cm}$ long and of uniform cross section is mounted on a meter scale, the ${ }_1$ and B coinciding with 0 cm and 100 cm marks respectively. The wire has a resistance $S=50 \mathrm{ohm}$. A $C$ along this wire, between $A$ and $B$ is called a variable point to which one end of an electrical ele connected. In the following questions this arrangement will be referred to as 'wire $A B$ '.Question: The emf of a battery is determined using the following circuit with 'wire AB '. The galvanometer shows zero deflection when one of its terminals is connected to point C . If the internal resistance of the battery is 4 ohm, its emf is