Distinguish between reactance and impedance of an ac circuit. Show that an ideal inductor in an ac circuit does not dissipate any power.

Reactance- It is the measure of opposition to flow of current in ac circuit comprising Inductor or Capacitor. Impedance- It is the measure of opposition to flow of current in ac circuit comprising Resistor, Capacitor and Inductor. \(\displaystyle \varepsilon=\varepsilon_{0} \sin \omega t\) \[\begin{aligned} I & =I_{0} \sin \left(\omega t-\frac{\pi}{2}\right)=-I_{0} \cos \omega t \\ P & =\varepsilon I \\ & =-\varepsilon_{0} I_{0} \sin \omega t \cos \omega t \\ & =-\frac{\varepsilon_{0} I_{0}}{2} 2 \sin \omega t \cos \omega t \\ P & =\frac{\varepsilon_{0} I_{0}}{2} \sin 2 \omega t \end{aligned} \]