2.1.3

Circuit Measurements

Test yourself

Measurements in Circuits

Several different properties of currents can be measured.

Illustrative background for AmmetersIllustrative background for Ammeters ?? "content

Ammeters

  • An ammeter measures the flow of current that passes through it.
  • Ammeters have to be connected in series (in the same loop of the circuit) with the electrical component whose current you are measuring. For example component X above.
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Voltmeters

  • Voltmeters measure the potential difference (voltage) between two points in a circuit. For example between two points either side of component X above.
  • Voltmeters must always be connected in parallel (on a separate branch of the circuit) with the two points being measured.
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Current vs potential difference

  • The current is a flow of charge. Current is measured through a component.
  • Potential difference is the energy used between two points in a circuit, therefore it is measured between two points either side of a component.
  • We describe this as the potential difference measured across a component.
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Galvanometers

  • An analogue meter uses a galvanometer, which is essentially a coil of wire with small resistance, in a magnetic field, with a pointer attached that points to a scale.
  • Current flows through the coil, causing the coil to rotate. To use the galvanometer as an ammeter, a small resistance is placed in parallel with the coil.
  • For a voltmeter, a large resistance is placed in series with the coil.

Jump to other topics

1Physical Quantities & Units

2Measurement Techniques

3Kinematics

4Dynamics

5Gravitational Fields

6Deformation of Solids

7Thermal Physics

8Oscillations

9Communication

10Electric Fields

11Current Electricity

12Magnetic Fields

13Modern Physics

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