A lamp consumes only 50% of peak power in an a.c. circuit. What is the phase difference between the applied voltage and the circuit current?
π6
π3
π4
π2
P=12Voiocosϕ⇒P=Ppeak ⋅cosϕ
⇒12Ppeak =Ppeak cosϕ
⇒cosϕ=12⇒ϕ=π3