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Alternating currentsEdexcel A-Level Physics: Mind map

What this mind map covers

  • Time properties
  • Peak value
  • r.m.s. value
  • Power
  • Exam tips

Exam questions on Alternating currents

  1. A sinusoidal alternating p.d. has a peak value of 12.0 V and a frequency of 50 Hz.
    Explain what is meant by the root-mean-square value of an alternating p.d., and why it is less than the peak value.2 marks
  2. A heater of resistance 46 Ω is connected to the 230 V r.m.s. mains supply, which has a frequency of 50 Hz.
    Calculate the r.m.s. current in the heater and the peak current.2 marks
  3. A student displays an alternating supply on an oscilloscope. The time-base is set to 5.0 ms per division and the Y-gain to 2.0 V per division. One complete cycle of the trace spans 4.0 horizontal divisions, and the trace reaches 3.0 divisions above and 3.0 divisions below the centre line.
    Calculate the period and the frequency of the alternating supply.3 marks
See the full worksheet

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).