Question

The rest positions of the needles in a Milliammeter and Voltmeter when not being used in a circuit are as shown in the figure. The 'zero error' and 'least count' of these two instruments are:



(1) (+ 4 mA, – 0.2 V) and (1 mA , 0.1 V) respectively
(2) (+ 4 mA, – 0.2 V) and (2 mA , 0.2 V) respectively
(3) (– 4 mA, + 0.2 V) and (2 mA, 0.2 V) respectively
(4) (– 4 mA, + 0.2 V) and (2 mA, 0.1 V) respectively

Answer 1

Total number of divisions on the milliammeter scale = 5
maximum value marked = 10 mA

Least count = $\frac{10\text{mA}}{5}=2\text{mA}$

Total number of divisions on the voltmeter scale = 10
maximum value marked = 1 V

Least count = $\frac{1\text{V}}{10}=0.1\text{V}$

On the milliammeter scale, zero error = $-2\times \text{(Least count)=- 2×2 mA= -4 mA}$

On the voltmeter scale, zero error = $2\times \text{(Least count)=2×0.1 V= 0.2 V}$

Hence, the correct answer is option 4.