Volt meter parts and functions e.g resistor etc

A voltmeter is an instrument used to measure the potential difference (voltage) between two points in an electrical circuit. Here are its main parts and their functions:

1. Moving Coil Galvanometer:

   • Function: This is the heart of the voltmeter. It's a sensitive device that detects and measures small electric currents. When current flows through its coil, it creates a magnetic field that interacts with a permanent magnet, causing the coil (and an attached pointer) to deflect. The amount of deflection is proportional to the current passing through it.

2. Series Resistor (Multiplier Resistor):

   • Function: A galvanometer itself has a very low resistance and can only handle small currents. To measure voltage, a high resistance resistor is connected in series with the galvanometer. This resistor serves two critical purposes:
     • It limits the current flowing through the galvanometer, protecting it from damage when measuring higher voltages.
     • It ensures that the voltmeter has a very high overall resistance. This is essential because a voltmeter must be connected in parallel across the component whose voltage is being measured. A high resistance ensures that very little current is drawn from the main circuit, thus not significantly altering the circuit's original voltage or current distribution.

3. Scale and Pointer:

   • Function: The pointer is attached to the moving coil of the galvanometer. As the coil deflects, the pointer moves across a calibrated scale, indicating the measured voltage value. The scale is marked in volts (V) or millivolts (mV), etc.

4. Terminals:

   • Function: These are the connection points (usually positive and negative) where the voltmeter is connected to the circuit.