here's a pdf my ex-physics teacher wrote up,
you'll find it invaluable rahul
-and anyone else
but yes, you're right
for those "small/minor" discuss questions
they should have asked for a describe or explain.
nothing high-order.
for that Q
you can't go into detail with a discuss verb
you'd talk about the EM spectrum and then link it to absorption by the atmosphere, which is as far as you can go.
all i've got is (taken from excel, but for those of you who dont have it...):
* absorption from the atmosphere
selective absorption from the earth's atmosphere of some bands of wavelengths, have implications for how and where we study electromagnetic radiations coming from objects in space.
ultraviolet and x-ray radiation is absorbed by the upper atmosphere; much of the infrared radiation is reflected by water vapour and gases in the atmosphere. as a result:
ground-based astronomy is restricted primarily to the visible and radio wave regions of the electromagnetic spectrum with some narrow 'windows' in the near infrared.
it follows that to use these other radiations effectively (ultraviolet and far infrared), we need to 'get above' the atmosphere. orbiting telescopes and space probes travelling to distant objects are used to examine information in these bands.
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yes, i rip off excel, but that's what i'll be doing in the trials/hsc and it has served me well just to regurgitate facts