Question

A thin uniform wire $AB$ of length $1m$ an unknown resistance $X$ and a resistance of $12\Omega$ are connected thick conducting strips, as shown in the figure.
A battery and a galvanometer (With a sliding jockey connected to it) are also available connections are to be made to measure the unknown resistance $X$ using the principle of Wheatstone bridge. Answer the following questions.
(a) Are there positive and negative terminals on the galvanometer
(b) copy the figure is your answer book and show the battery and the galvanometer (With jockey) connected at appropriate points.
(c) After appropriate connections are made, it is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of $60cm$ from $A$. Obtain the value of the resistance of $X$.

Answer 1

(a) No

(b) figure shown

(c) Bridge is balanced

$\frac{R_{AJ}}{R_{JB}}=\frac{0.6\rho }{0.4\rho }=\frac{12\Omega }{X}\Rightarrow X=8\Omega$ where $\rho$ is resistance per unit length.