PHYA5 ~ 20th June 2013 ~ A2 Physics

I mean you can kind of swing the telescope lens around to look at other objects without the eye having to refocus, because ANY object you choose to look at through the telescope is at infinity. This is a situation where an astronomer is using the telescope to examine many objects, over a long period of time - not just one.

I dug up this:
For comfortable viewing, the final image formed by the eyepiece (ocular) should be at infinity. Although
the human eye can focus on objects which are 25 cm away to infinity, the eye muscles are most relaxed
when viewing objects which are very far away.

from here: http://n.ethz.ch/~geric/download/4.%20Semester/Physik%20II/FS12/Blatt11_2012_Lsg.pdf

Which is, weirdly. a paper used by the Swiss Federal Institute of Technology in Zurich.

I haven't been able to find any other reasons that the image is formed at infinity, so I'm just going with that.

I mean you can kind of swing the telescope lens around to look at other objects without the eye having to refocus, because ANY object you choose to look at through the telescope is at infinity. This is a situation where an astronomer is using the telescope to examine many objects, over a long period of time - not just one.

I dug up this:
For comfortable viewing, the final image formed by the eyepiece (ocular) should be at infinity. Although
the human eye can focus on objects which are 25 cm away to infinity, the eye muscles are most relaxed
when viewing objects which are very far away.

from here: http://n.ethz.ch/~geric/download/4.%20Semester/Physik%20II/FS12/Blatt11_2012_Lsg.pdf

Which is, weirdly. a paper used by the Swiss Federal Institute of Technology in Zurich.

I haven't been able to find any other reasons that the image is formed at infinity, so I'm just going with that.

Could someone please explain standard candles to me? I get that they are like a set 'measurement' from the peak of a type 1a supernovae but how do we actually determine distances from them? I know that we know he absolute magnitude but how do we work out the absolute magnitude to be able to determine the distance? And also, for how long does a type 1a supernova stay at an absolute magnitude of -19.2? Is it for substantial period of time for it to be observed?

Finally, I have query to the big bang theory. Is the increased rate of expansion evidence for the big bang theory? It just noted down as that in my book, but I don't actually understand why :/

This is going to be the easiest 100 UMS, without a doubt.

The easiest option by far is applied physics.
After all my maths exams, ill be glad to have a nice easy one to end it.

Type 1a supernovae can be used as standard candles as they reach the same peak value of M (absolute magnitude) of around -19.3. The -19.3 is the value for M taken after around 20 days after the start of increase in brightness. From these measurements and using m-M=5log(d/10), we can measure the distance to these galaxies. However, by using red shift measurements and Hubble's Law (which assumes a constant rate of expansion), these supernovae are dimmer than predicted. This must mean that the expansion of the Universe is accelerating and some form of 'dark energy' is driving this expansion.

I think they measure the brightness of the star - i.e. the watts per square m of light energy from the star that reaches the Earth
and then they convert it to the magnitude scale using m = -2.5logb where b is the brightness in watts per m^2 and m is the magnitude

Just got this question from a friend of mine and couldn't get the right answer. I keep getting 10^-12 which is definitely wrong. It should be 10^12. I used the idea of Power(S)*d(s)^2 = Power (Q)* d(Q)^2 and then rearranged. By the way S represents for the sun and Q for the quasar. Thank you