Question

Which expression gives instantaneous power in a pure resistor AC circuit?

Options

• \[p=vi=v_mi_m\sin\omega t\]

• \[p=vi=\frac{1}{2}v_mi_m\]

• \[p=vi=v_mi_m\sin^{2}\omega t\]

• \[p=vi=v_mi_m\cos 2\omega t\]

Answer 1

Instantaneous power is \[p=vi\]. Multiplying \[v=v_m\sin\omega t\] by \[i=i_m\sin\omega t\] gives \[p=v_mi_m\sin^{2}\omega t\].