Question

(a) In a metre bridge [Fig.], the balance point is found to be at 39.5 cm from the end A, when the resistor Y is of 12.5 $\Omega$. Determine the resistance of X. Why are the connections between resistors in a Wheat stone or meter bridge made of thick copper strips?(b) Determine the balance point of the bridge above if X and Y are interchanged.(c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?

Answer 1

$\begin{array}{c}\frac{x}{y}=\frac{L_1}{\left(100-L_1\right)}\\ x=12.5\\ L_1=39.5\\ L_2=100-L_1\\ =60.5\\ \frac{12.5}{y}=\frac{39.5}{60.5}\end{array}$
If x and y exchange
$\begin{array}{c}\frac{y}{z}=\frac{L_1}{100-L_1}\\ \frac{y}{12.5}=\frac{39.5}{60.5}\\ y=\frac{39.5}{60.5}\times 12.5\\ =8.161\end{array}$