# 3.10    (a) In a meter bridge [Fig. 3.27], the balance point is found to be at 39.5 cm from the end A, when the resistor Y is of 12.5 Ω. Determine the resistance of X. Why are the connections between resistors in a Wheatstone or meter bridge made of thick copper strips?   (b) Determine the balance point of the bridge above if X and Y are interchanged.

H Harsh Kankaria

If X and Y are interchanged.

Then, X = 12.5 Ω , Y = 8.2 Ω

We know, for a meter bridge, balance condition is:

$\frac{X}{Y} = \frac{l_1}{l_2} = \frac{l_1}{100 - l_1}$

$\\ \implies \frac{12.5}{8.16} = \frac{l_1}{100 - l_1} \\ \\ \implies 1.53(100 - l_1) = l_1 \\ \implies 2.53l_1 = 153$

$\therefore l_1 =60.5 cm (from \ point\ A)$

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