# Measurements

### Explanation of question 7

A moving coil microammeter has an f.s.d. of 200A and resistance 20. The value of shunt resistance required such that the instrument will have an f.s.d. of 1mA is

1. 5
2. 4
3. 3.33
4. 0.20

The answer is :- 1

Here the shunt needs to carry a current of 1mA - 200A = 800A. The voltage drop across the shunt = voltage across the meter = 200A x 20 = 4mV. Thus resistance of shunt = voltage across shunt / current through shunt = 4mV / 800A = 5

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