Question

Why is voltmeter connected in parallel in a circuit?

Answer 1

Actually, voltmeter is used to measure the voltage of the circuit and and it is connected parallel in the circuit because things which are connected parallel experience same potential difference and it is used to measure potential difference between two points.
Hope it will satisfy you.

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.