Measuring Devices ( Galvanometer, Voltmeter and Ammeter & Meter Bridge ): Practice Problem & Solution
In a Wheatstone's bridge all the four arms have equal resistance R. If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is: (2003)
Solution Explained:
To solve this problem, we apply the core principles of Measuring Devices ( Galvanometer, Voltmeter and Ammeter & Meter Bridge ). Understanding the underlying formula is key to arriving at the correct answer below:
Since all four arms have resistance $R$, the ratio of adjacent arms is equal ($R/R = R/R$), making it a balanced Wheatstone bridge.nNo current flows through the galvanometer arm, so it can be ignored.nEquivalent resistance $R_{eq} = \frac{(R+R)(R+R)}{(R+R)+(R+R)} = \frac{2R \times 2R}{4R} = R$.
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