Question

The instantaneous current from an a.c. source is I =5 sin(314t)ampear .what are the average and RMS value of the current?

Answer 1

avg current in ac is always zero due to changing directions. so avg current is zero

RMS current is equal to
$5 \div \sqrt{2}$

Answer 2

The average value of current is zero for complete cycle and the RMS value of current is 3.535 ampere.

Average value of complete cycle is zero.

In first half cycle the average or mean value of current is

=+2/3.14 i =0.637 i where i is peak value of current.

In second half of cycle the average value of current is

= -2/3.14 i= -0.637 i

So average value of complete cycle is zero.

According to question we have:-

I=5 sin(314t) ampere where i=5 peak value of current

RMS value of current =i/(2)^1/2 = 0.707i

Where i is peak value of current i=5

RMS=0.707*5=3.535 ampere.