Introduction
 

Alternating current (AC) is an electric current that repeatedly changes direction and magnitude. It is the form of electricity supplied to homes and businesses because it can be transmitted efficiently over long distances using transformers. In this topic, students learn how alternating currents are produced, how they are represented using sinusoidal waveforms, and how quantities such as peak and root mean square (rms) values are related.
 

AQA A Level Physics Specification: 3.7.4.4 Alternating Currents
 

What You Need to Know
 

• Describe the characteristics of alternating current (AC).

• Explain how an alternating emf is generated by a rotating coil in a magnetic field.

• Interpret current-time and voltage-time graphs for alternating currents.

• Define the frequency and period of an alternating current.

• Distinguish between peak and root mean square (rms) values.

• Apply equations relating peak and rms current and voltage.

• Explain why mains electricity is supplied as alternating current.

• Solve quantitative problems involving alternating current circuits.
   

Downloadable Topic Pack
 

Alternating Currents Topic Pack Exam Questions and Answers

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Related Topics
 

• Electromagnetic Induction

• Magnetic Flux Density and Flux Linkage

• Transformers

• National Grid

• Root Mean Square (RMS) Values