Question

What is a voltmeter? why is it connected in parallel with the circuit?

Answer 1

voltmeter measures voltage in a circuit...
its connected in parallel and has high resistance so it would not allow current to pass through it.

Answer 2

Ammeter:-

An ammeter is just a converted Galvanometer and measures the current flowing through the circuit by showing proportional deflection. An ammeter is formed by connecting a Galvanometer with a low resistance in parallel.

$\bigstar$So the ammeter is connected in series with the circuit elements and the measures the current flow in a circuit.

Voltmeter:-

A Voltmeter is also a converted Galvanometer which measures the amount of Voltage (or) in other words the potential difference accross two points in a circuit. A voltmeter is formed by connecting a Galvanometer in series with a high resistance.

$\bigstar$So the Voltmeter is attached in parallel in a circuit and measures the voltage in a circuit

And if this is not maintained then there is a high chance for the ammeter to get damaged due to low resistance.