Question

To minimize voltmeter loading
1. Voltmeter operating current has to be very small
2. Voltmeter operating current has to be very high
3. Resistance connected in series with the coil should be low
4. Resistance connected in parallel with the coil should be high

Answer 1

Correct Answer - Option 1 : Voltmeter operating current has to be very small

Loading effect in voltmeter:

• The loading effect is the degree to which a measurement instrument impacts electrical properties like the voltage, current, and resistance of a circuit.
• In general, the resistance of an ideal voltmeter is infinite so that the voltmeter does not alter the circuit current.
• But, in the practical world, the value of resistance of the voltmeter is not infinity it is a high value only.
• If we use voltmeter in small resistors circuit then there is no much change in the quantities of the circuit.
• If we use voltmeter in high resistor circuits then the resistance of voltmeter is less when compared to the circuit resistance, this will act as a shunt path for the current and therefore the voltage drop across the resistor where we want to measure the voltage will be less.
• Because of this, the reading of the voltmeter will not be the actual voltage drop rather it will be lower than actually existed before the connection of the voltmeter. This is called a Loading effect of the voltmeter.
• ​As voltmeter produces deflection by measuring a portion of load current drawn from the circuit under test.
• To minimize voltmeter loading, this current (required for the operation of voltmeter) drawn should be very small.