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Reading a sinusoidal AC graph

Reading a sinusoidal AC graph

Sine-wave graph of alternating current against time with peak current, rms level, period, and zero crossings labelled

An alternating current changes direction periodically, unlike direct current which flows in one direction only. In many exam questions the waveform is sinusoidal, so the instantaneous current can be written as I=I0sin⁡(2πft)I = I_0 \sin(2\pi ft)I=I0​sin(2πft). The same pattern applies to voltage, with V=V0sin⁡(2πft)V = V_0 \sin(2\pi ft)V=V0​sin(2πft).

Alternating currents and rms values Lesson

  1. A Level
  2. /Physics
  3. /Alternating currents and rms values

Step-by-step lessons covering Edexcel A Level Physics Alternating currents and rms values for A Level Physics. Each lesson works through exam-style questions in Paper 1, Paper 2 and Paper 3 format. Physics is one of the most mathematically demanding A Levels -- at least 40% of the marks across the three papers require maths skills at Level 2 (GCSE) standard or above, so build calculation and graph-handling fluency alongside the conceptual content from the start.

Lessons