Voltage, V=V0​cosωt Current, i=i0​sinωt or i=i0​cos(ωt−2π​) Power dissipated in an AC circuit is given by,P=Irms​Vrms​cosϕ where Irms​= rms value of currentVrms​= rms value of voltageϕ= phase difference between current and voltageHere, ϕ=π/2 ⇒cosϕ=cos2π​=0 ∴P=Irms​Vrms​×0=0