Question
Question: The potential difference V and the current i flowing through an instrument in an ac circuit of frequ...
The potential difference V and the current i flowing through an instrument in an ac circuit of frequency f are given by V=5cosωt volts and I = 2 sin ωt amperes (where ω = 2πf). The power dissipated in the instrument is
A
Zero
B
10 W
C
5 W
D
2.5 W
Answer
Zero
Explanation
Solution
V=5cosωt=5sin(ωt+2π) and i=2sinωt
Power =Vr.m.s. ×ir.m.s. ×cosϕ = 0
(Since ϕ=2π, therefore cosϕ=cos2π=0 )