General Electric Devices- Ammeter & Voltmeter



It is an instrument used to measure the electric current in a circuit. It is always connected in series in a circuit. It has low resistance(practically). Ideally ammeter’s resistance must be zero

Electric Circuit for Ammeter

It is a closed path along which the electric current flows.

Electric Circuit for Ammeter

  • The electrons can only flow when there is the difference of electric potential.
  • For example “water flowing through a tube”. It is only possible when there is high pressure at one side and low at another side, then it will move from high pressure to low pressure.
  • In case of electric current, the flow of charge is made possible due to chemical action within a cell that generates the potential difference across the terminals of the cell.

Electric potential Difference

It is defined as the work done in carrying a unit charge from one point to another in an electric circuit.

Electric potential Difference

SI unit of potential difference is Volts. Denoted by “V”. It is named after Alessandro Volta.

One Volt

When 1 Joule of work is done in carrying one coulomb (1C)of charge from one point to another of a current carrying conductor then the potential difference is said to be IV.



A voltmeter is an instrument, used to measure the potential difference and represented by the symbol V in an electric circuit. It is always connected in parallel across the points between which the potential difference is to be measured. It has high resistance.

Circuit Diagram for Voltmeter

Circuit Diagram for Voltmeter

A circuit diagram (electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an electric circuit.



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