In a meter bridge experiment, with resistance R in the left gap and unknown resistance X in the right gap, the null point is found at 75 cm. If R = 3X, what is the value of X?

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Question 11: Meter Bridge Experiment

Step 1: Set up the balance condition for the initial state.
In a meter bridge, the balance condition is $\frac{R_{left}}{R_{right}} = \frac{l}{100-l}$.
Initially, the null point is at $l_1 = 75$ cm from terminal A. Resistance R is in the left gap and unknown resistance X is in the right gap.

$$\frac{R}{X} = \frac{75}{100-75} = \frac{75}{25} = 3$$

So, $R = 3X$ (