Voltmeter:

1. Purpose:

   • A voltmeter is used to measure the voltage or potential difference across two points in an electrical circuit.

2. Connection:

   • Connected in parallel to the component or portion of the circuit where the voltage is to be measured.

3. Resistance:

   • Ideally, a voltmeter should have infinite resistance to minimize its impact on the circuit and ensure accurate voltage measurement.

4. Reading:

   • Displays the voltage in volts (V) and provides information about the electrical potential at the measured points.

5. Usage:

   • Used to determine the potential difference across various components in a circuit, helping to analyze and troubleshoot electrical systems.

6. Installation:

   • Installed in parallel to the circuit, so it does not disrupt the flow of current and accurately measures the voltage at the specified location.

Ammeter:

1. Purpose:

   • An ammeter is used to measure the electric current flowing through a circuit or a specific part of it.

2. Connection:

   • Connected in series with the component or portion of the circuit through which the current is to be measured.

3. Resistance:

   • Ideally, an ammeter should have negligible resistance to minimize voltage drop across it and ensure accurate current measurement.

4. Reading:

   • Displays the current in amperes (A) and provides information about the flow of electric charge through the measured points.

5. Usage:

   • Used to monitor and measure current in various sections of a circuit, aiding in the analysis of power consumption and circuit behavior.

6. Installation:

   • Installed in series with the circuit, allowing the entire current to pass through the ammeter, providing an accurate measurement of current flow.

In summary, the key difference lies in their purpose, connection, and where they are placed in a circuit. A voltmeter measures voltage and is connected in parallel, while an ammeter measures current and is connected in series. Both instruments are essential for understanding and troubleshooting electrical circuits.