Question

If the current in an AC circuit is represented by the equation, i=5sin(300t-pi/4) Here t is in second and in an ampere, calculate (a) peak and rms value of current (b) frequecne of AC (c) average current.

Answer 1

Given,

Current in AC circuit,

I =I○sin (300t -pi/4) .........(i)

We know the current in AC circuit is

I =I○sin (wt-phi) ..........(ii)

Where ,

I○=peak current

w =angular frequency

Phi=phase difference

(a) By comparing equation (i)&(ii)

I○=5

By using formula ,

I rms=I○/1.414

Since, I rms=5/1.414 = 3.536 A

(b) by comparing equation (i)&(ii)

w=300

By using formula,

w=2pi n

where ,w(omega )= angular frequency

n =frequency

n=300/2 pi=47.77 Hz

(c) average current =2I○/pi

=2×5/3.14

=3.18A