00:01
Alright, so it is asked that which phasor graph currently, correctly represents the state of this circuit at t is equals to 3t by 4, right.
00:13
First of all this is very basic thing, okay.
00:16
So this is a sine wave, sine wave, okay.
00:21
And this is looking like a cos wave, cosine wave, right.
00:27
So cosine wave is ahead of sine wave, right.
00:31
So whenever you make a diagram, so whatever is ahead, so we are taking from positive x axis, so suppose this is behind because when you extend cos wave, so this is ahead of it, this is started from here, so that means cosine wave would be 90 degrees ahead of it, right.
00:54
So 90 degrees ahead of it, since vl is plus pi ahead of il, therefore you can say angle between them is 90 degrees first of all, right.
01:28
And secondly, this is first condition, okay.
01:32
And second condition is vl should be ahead, right, of il from positive x axis direction, right.
01:54
So let us suppose first it was il, right, let us say this is il and this would be vl.
02:03
So this is for sure that when you move from like anti -clockwise direction, right, so vl would be ahead of it.
02:13
This will be starting, il would be starting from here, but it will be ahead of 90 degrees, right.
02:21
So that means there should be an angle which is 90 degrees and it is anti -clockwise from the positive x axis, right.
02:29
So what are like angles you could say, these both conditions are satisfied.
02:35
These both conditions are satisfied when you see in the first problem, vl is here, right.
02:43
So vl cannot be, vl has to be ahead of it, okay...