- Write the principle of working of a metre bridge.
- In a metre bridge, the balance point is found at a distance $l_1$ with resistances R and S as shown in the figure.
An unknown resistance X is now connected in parallel to the resistance S and the balance point is found at a distance $l_2$. Obtain a formula for X in terms of $l_1$, $l_2$ and S.
CBSE OUTSIDE DELHI - SET 1 2017
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- The principle of working of a meter bridge is same as that of a balanced Wheatstone bridge.
When $\text{i}_{\text{g}}=0$, then $\frac{P}{Q}=\frac{R}{S}$
- $\frac{R}{S}=\frac{l_1}{100-l_1}$
$\frac{R}{\Big(\frac{XS}{X+S}\Big)}=\frac{l_2}{100-l_2}$
On solving, we get $X=\frac{l_1S(100-l_2)}{100(l_2-l_1)}$
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