Question

The voltage and current in a series AC circuit are given by V = V₀cos ωt and i = i₀ sin ωt. What is the power dissipated in the circuit?

Answer 1

Voltage, V = V₀cos ωt
Current, i = i₀ sin ωt or i = i₀ cos (`wt - pi/2`)
Power dissipated in an AC circuit is given by,
`P = I_rms  V_rms cos Ø`,
where I_rms = rms value of current
V_rms= rms value of voltage
ϕ = phase difference between current and voltage
Here, ϕ = `pi`/2
⇒ `cos Ø = cos  pi/2  = 0`
∴` P = Irms Vrms xx o = 0`