Measurements

Explanation of question 10

A moving coil instrument has an f.s.d. of 1mA. When the instrument is connected to a 14.9k multiplier it can read up to 15V. The instrument resistance is

1. 15
2. 100
3. 15k
4. 15.lk

The answer is :- 2

In this question we must first ascertain how much voltage is dropped across the multiplier and how much across the meter. From Ohm's law, the voltage across the multiplier = 14900 x 0.001 = 14.9V. Thus only 0.1V is across the meter. From Ohm's law (again) R=V/I = 0.1/0.001 = 100