In previous unit you have learnt that the output e.m.f. of a typical ac generator has a sinusoidal pattern. It is a common wave form in most electronic circuits. But alternating currents and potential differences which are not sine waves can be produced by electronic circuits. Figure 1 shows other possible wave forms. Each of them change the directions and magnitude periodically

Square wave forms appear in computer circuits, saw tooth wave forms in TV receiver circuits and sinusoidal wave forms in heaters.

Key Terms

• Alternating current.
• Waveform.
• Rectification
• Impedance
• Power factor