Question 4
(a) State:
(i) how the range of a voltmeter can be extended.
(ii) two advantages of a moving-coil instrument.
(b) A moving-coil instrument having a coil of resistance 100 Ω requires a current of 1 mA to give a full scale deflection.
(i) Calculate the value of the series resistor required for the instrument to have a range of 0 - 200 V.
(ii) Draw the circuit diagram of the arrangement.
OBSERVATION
(a) (i) The range of a voltmeter can be extended by connecting a high resistance known as multiplier in series with the instrument.
(ii) Advantages of a moving-coil instrument.
- High sensitivity.
- Even scale or uniform scale.
- Unaffected by stray magnetic fields.
- Low power consumption.
- No hysteresis loss
(b) Given a moving-coil instrument with:
resistance = 100 Ω;
current = 1 mA to give a full-scale deflection.
(i) Value of the series resistor required for the instrument to have a range of 0 - 200 V.
Value of series resistor
Rm = 
OR 
= 199,900 Ω
=199.9 k Ω =199.9 k Ω
(ii) Circuit diagram of the arrangement.
Many of the candidates attempted this question Only few of those who attempted the question did not do the question correctly Many did not put unit for the answer.