00:01
So we have the very large array radio interferometer, which is 27 radio dishes.
00:08
And so i'm not going to draw a whole 27.
00:10
I want to be here all day.
00:11
They're all the same size, though, so let's make them almost the same size.
00:14
There are 27 of these, though.
00:22
And they each have a diameter of 25 meters.
00:27
So what we want to find is the collecting area, which is basically the area that is presented to the incoming radio waves or electromagnetic radiation.
00:35
Of course light is just part of the em spectrum.
00:39
So in real life, of course, these radio dishes are parabolic because they want to focus to some point.
00:45
And then there's, you know, the little radio receiver sticking somewhere out here.
00:52
But if you look really far away, because, of course, the stars are basically infinitely far away for practical purposes, they just kind of see the disc here.
00:59
So we can model it as a bunch of circles.
01:03
So to find the total collection anyway, first you know the area of a circle, which is equal to pi r squared, but we have diameter though, and we know that radius is diameter over two squared.
01:18
And so when we work that out, we see that the area in terms of diameter is pi over four diameter squared.
01:26
So the total area of the collection area, we'll call it the area of collection, ac, is just going to be 27 times this because we have 27 circles.
01:37
And so it's going to end being 27 pi over 4.
01:40
The diameter which we were given, 25 meters.
01:44
We square that.
01:46
And so we see that the collection area is equal to 13 ,254 meter squared...