SSC JE Electrical Engineering 2017 Set 3 Paper

Question : 145 of 200

Marks: +1, -0

Energy stored in a capactior over a cycle when excited by an a.c. source is____

Solution:

In capacitor, current lead voltage by 90° in time
Let

V = V_m \sin ωt = I_m \cos ωt

Now,

P = VI = V_m \sin ωt × I_m \cos ωt

={V_mI_m}/2\sin2ω t

Now, Average power

P_\av=∫↖{2π} ↙{0}Pdt

∫↖{2π} ↙{0}{V_mI_m}/2\sinω tdωt

{V_mI_m}/2∫↖{2π} ↙{0}\sin2ω t∝ωt

= 0

Go to Question:

Prev Question

Next Question