Ammeters and voltmeters are electrical instruments used to measure different electrical quantities, and they serve distinct purposes in the context of electrical circuits. Here are five key differences between an ammeter and a voltmeter:
Quantity Measured:
Ammeter: An ammeter is used to measure electric current in a circuit. It is connected in series with the circuit, and it measures the flow of electric charge (current) passing through the circuit.
Voltmeter: A voltmeter is used to measure voltage, which is the potential difference between two points in an electrical circuit. It is connected in parallel across the component or portion of the circuit where the voltage is to be measured.
Connection in a Circuit:
Ammeter: An ammeter is connected in series with the circuit under measurement. It becomes part of the circuit through which current flows, allowing it to measure the current passing through that part of the circuit.
Voltmeter: A voltmeter is connected in parallel across the component or portion of the circuit for which voltage is to be measured. It is connected across the points between which the voltage is to be determined.
Resistance:
Ammeter: An ammeter is designed with very low internal resistance to minimize its impact on the circuit’s current being measured. This low resistance ensures that the ammeter does not significantly affect the current it is measuring.
Voltmeter: A voltmeter has a high internal resistance to prevent drawing too much current from the circuit being measured. The high resistance ensures that the voltmeter does not significantly alter the voltage across the points it is measuring.
Reading Scale:
Ammeter: The scale of an ammeter is calibrated in units of current, such as amperes (A). It provides a direct reading of the current flowing through the circuit.
Voltmeter: The scale of a voltmeter is calibrated in units of voltage, such as volts (V). It provides a direct reading of the potential difference between the points across which it is connected.
Functionality:
Ammeter: Ammeters are used to measure current in various electrical components, such as resistors, capacitors, and other devices, to assess the flow of electric charge through them.
Voltmeter: Voltmeters are used to measure voltage across components, helping to determine the potential difference and electrical energy associated with different points in a circuit.
In summary, ammeters measure current and are connected in series, while voltmeters measure voltage and are connected in parallel. Their internal resistances, readings, and functionalities are tailored to their specific measurement purposes in electrical circuits.