A student connects an oscilloscope to two different supplies, P and Q.
Figure: The oscilloscope traces produced by two different supplies, P and Q

Write down which supply, P or Q, produces an alternating potential difference.
Give one reason for your answer to part a).
The UK domestic mains supply has a frequency of 50 Hz.
Write down what the frequency tells you about the mains supply.
40 exam-style questions on AQA GCSE Physics 2.3 Domestic uses and safety, covering 2.3.1 Direct and alternating potential difference and 2.3.2 Mains electricity. Each one has a worked solution and a mark scheme showing where the marks go.