Question

What is resistance of voltmeter?

Answer 1

We know that a voltmeter is a device which measures the voltage drop across any electrical instrument or circuit. We also know that the voltmeter is connected in parallel connection across the points where the voltage needs to be measured.

Complete answer:
An voltmeter works on the principle of electro-magnetic induction. A voltmeter is just a modified version of a galvanometer.
A galvanometer is an electronic instrument device, which detects the electric current in the circuit. Here, the intensity of current is generally indicated by the movement of the magnetic needle. Thus, the principle of a galvanometer is as follows:
When a current carrying coil is placed under a magnetic field, then the coil experiences a torque.
This torque is also called the magnetic torque, due which the magnetic needle moves. The deflection of the needle is proportional to the current in the circuit.
We know from Ohm’s law, that current and voltage are directly proportional to each other, then we can say that the galvanometer can be used to detect the voltage in the circuit, by making small modifications.
To convert a galvanometer to a voltmeter, an infinitely high resistance is connected in series with a galvanometer.
Thus ideally, an voltmeter has very high resistance, to avoid the flow of current through it, when connected in parallel with the resistor of interest,

Note:
A galvanometer can be converted to both an ammeter and a voltmeter. To convert the galvanometer to an ammeter, it is connected with a very small resistance, whereas to convert it into a voltmeter it is connected to a very high resistance.