Circuit Measurements
Physics: Cambridge International GCSE Supplement, topic 4.5.1
Measurements in Circuits
Several different properties of currents can be measured.
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.
Voltmeters
- Voltmeters measure 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 the charge passing a point per unit time. Current is measured through a component.
- Potential difference is the work done by a unit charge passing through a component.
- We describe this as the potential difference measured across a component.
Test yourself on Circuit Measurements
What instrument is used to measure current?
Which of the following are true of measurements of a circuit?