00:01
Question number 37 is asking us what the size of the moon's image would be in the focal plane of a telescope that has a very large focal length of 250 meters.
00:13
Now, if you recall from the text, the focal length of a telescope is the distance between the main eyepiece of the telescope and the length of the telescope.
00:30
Lens and that is directly what affects the size of the image that you can see in the focal plane of the telescope.
00:43
So this distance that i'm illustrating here would be our focal length and the focal plane would be this part here.
00:56
Now for the very large telescope we're given a focal length of the i could call that flvlt is equal to 250 meters.
01:12
And the focal length or fl of our amateur telescope is 1 .5 meters.
01:23
Now, the way to deduce how big the image will be in the 250 meter telescope is to calculate its magnification compared with that of the 1 .5 meter amateur telescope.
01:40
The way we do that is just divide 250 meters.
01:47
That's the focal length of the very large telescope...