Question

why is the voltmeter connected in parallel in a circuit

Answer 1

This is necessary because objects which are parallel experience the same potential difference.

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.