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: In the adjacent circuit a resistance $R$ is used. Initially with 'wire AB' not in the circuit, the galvanometer shows a deflection of $d$ divisions. Now, the 'wire AB ' is connected parallel to the galvanometer and the galvanometer shows a deflection nearly $d / 2$ divisions. Therefore