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GCSE Combined Science · key term
An electric current that repeatedly reverses direction.
Used by AQA and Edexcel
Specification 6.2.3.1, 6.6.2.3 · Paper 5, Paper 6
Revise: Direct and Alternating Potential DifferenceIn a simple circuit, this drives a current first in one direction and then in the opposite direction. This is alternating current, abbreviated ac.
Paper 5, Paper 6
An electric current that repeatedly changes direction.
Revise: Transformers and the national gridThe alternating current in the primary coil repeatedly changes direction, producing a changing magnetic field. The iron core links this changing field to the secondary coil. The changing magnetic field through the secondary coil induces an alternating potential difference across it.
For radio-wave questions, link oscillating charge in the transmitting circuit to the radio wave, then to an alternating current in the receiving circuit.
State that the induced alternating current has the same frequency as the absorbed radio wave—not necessarily the same size.
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