Question

An ideal voltmeter has:
A. Zero resistance
B. Finite resistance less than but greater than $0$
C. Resistance greater that but less than infinity
D. Infinite resistance

Answer 1

Hint: Voltmeter is used to measure the voltage through the circuit and is connected in parallel with the main circuit. For an ideal voltmeter no current should follow through it, all the current must pass through the connected resistance parallel to it to measure the voltage accurately.

Complete solution Step-by-Step:
Voltmeter is used to measure the voltage between two points of the circuit and is connected in parallel with the main circuit. It is present in both digital and analog form. In analog voltmeter, there is a pointer which moves on a scale in proportion to the voltage in the circuit. Whereas in a digital voltmeter, it displays a numeric value.

 For an ideal voltmeter no current should flow through it, all the current must pass through the connected resistance to measure the voltage accurately. This happens only when the voltmeter has high resistance. But an ideal voltmeter doesn’t exist in real life, as the name suggests it is a hypothetical case.

For an ideal voltmeter, it must have infinite resistance to measure the voltage drop across the circuit accurately.
Hence the answer is, D. infinite resistance.

Note:
Analog voltmeter, follows the principle of moving coil galvanometer, whereas a digital voltmeter uses an integrating converter to convert the analog form to a digital display. Voltmeters are less accurate with the measure of electricity, as they are having high resistance. They have a maximum range of 0-20V. And the range can be increased by connecting the resistor in series with the voltmeter i.e.to increase the resistance. Similarly, the range can be reduced by connecting resistors in parallel.