Why is voltmeter always connected in parallel? What will happen if it is connected in series?

Hint:To solve this question. We should know about the following terms.
Voltmeter: A voltmeter is a device that measures voltages of direct or alternating electric current on a scale that is commonly in volts, millivolts (0.001 volt), or kilovolts (1,000 volts). Many voltmeters are digital, with numerical displays for readings.
So, to solve this question we should first understand how it works.


Complete step by step solution:
Working of voltmeter:
Its operation is based on the Ohm's law idea. “Voltage across a resistance is precisely proportional to the current travelling through it,” according to Ohm's law. When a full-scale current flows through a basic meter, there is a potential difference across its terminals. The voltmeter is represented by a circle with a letter V contained within it.
It is always connected in parallel because A voltmeter is always connected in parallel to the component in a circuit that needs to be tested for voltage. A polarity sign can be found on a DC voltmeter. To acquire a meter deflection, connect the positive (+) terminal of the volt-meter to the higher point of potential and the minus (-) terminal to the lower point of potential.
There are no polarity indicators on an AC voltmeter, but it can still be connected. However, the voltmeter is still connected in parallel to the component that is being measured in this scenario.
A high-voltage voltmeter is made by connecting a resistance in series with a meter mechanism that can measure full scale voltage. That is why it will connect in series.

Note:
An ammeter (short for ampere meter) is a device that measures the current in a circuit. The term comes from the fact that electric currents are measured in amperes (A). The ammeter is normally wired in series with the circuit that will be used to measure the current.