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In a Wheatstone bridge with the four resistances shown, a galvanometer of resistance 15 ohm bridges points B and D. With a steady 10 V applied across A and C, find the current flowing through the galvanometer.

1. 2.44 microA
2. 2.44 mA
3. 4.87 mA
4. 4.87 microA

Correct answer: 4.87 microA

Solution

Solving the unbalanced bridge with Kirchhoff's loop and junction equations for the given arm resistances yields a very small galvanometer current of about 4.87 microamperes.

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