cosmology exam!!!!!!!!

hey

I have a cosmology OCR A exam coming up fairly soon!!!!!

I understand my concepts but find it hard to interpret the questions. I have also done past papers to help me out on this.

Please can anyone out there advise me more on this??????

Thanks in advance

xxxxx

Reply 1

Ekpyrotic

13

Hey,

I sat this last year and got 98%. I'll lend as much of a hand as possible; can you spell out your worries a little more specifically? Maybe use a troubling question as an example for how you find it hard to approach.

Reply 2

rose27

OP

Ekpyrotic

Hey,

I sat this last year and got 98%. I'll lend as much of a hand as possible; can you spell out your worries a little more specifically? Maybe use a troubling question as an example for how you find it hard to approach.

I will be very grateful to you for helping me out on this.

calculation part and thought experiments + muons are fine.

I will give you example of three questions:

1 State and explain the evidence in support of the big bang model including microwaves background radiation (4 marks)

The mark scheme;s answer:
3k temperature, black body spectrum, uniform, isotropic, shows ripples
universe much hotter in past
hubbles law - expanding universe
implies cooling
helium abundance
He formed in big bang

2 describe the important properties of cosmic microwave background rad and how the standard universe explains these properties. explain their significance as evidence for past evolution of the universe (5)

Answer :
3k temperature, black body spectrum, uniform, isotropic, shows ripples
produced when matter-rad decoupled
originally gamma rad
gamma rad red shifted to microwaves
evidence universe began with big bang.

3 describe how the MBR is thought to have risen in standard Big bang cosmology (5)

Rad origin from bb
early universe very hot
matter -rad equilibrium
universe cools/ expands
atoms form / universe becane transparent.

So for this answer - 3 I would have also added
universe singular
originally gamma rad
gamma rad red shifted to microwaves

Is this relevent, if not then why?

I have a massive problem on interpretting the questions. Like writing what answer for which question ! Please help me on this.
so for Questions 1 and 2 i would have written a similar answer :

3k temperature, black body spectrum, uniform, isotropic, shows ripples
after this i would not know what to write?

Having 98% is a victory. Please tell me how did you revise for the exams - cosmology?

Reply 3

rose27

OP

some more questions!
spectroscopic analysis of stralight reveals the presence of dark lines in the spectrum. Explain how these absorption lines occur? (2)

I would write:

atoms in somewhat cooler region of stellar atmosphere, absorbs exactly the same wavelength of radation as it emits.

2 outline how the composition of stellar atmosphere may be obtained from stellar spectra? (2)

My answer:
comapre the dark line to the spectra on earth
elements have unique spectra

what is wrong in this?

Reply 4

Ekpyrotic

13

Ok, you're misunderstanding the material here. When's the exam?

Reply 5

Sarky

18

I thought this said cosmetology...like make up and stuff.

Good luck for your exam :biggrin:

Reply 6

Ekpyrotic

13

My advice:

1. Go through all the exam papers and grab the long answer questions. Just paste them all into an empty document.

2. Use this website http://www.harmsy.freeuk.com/Alevelreq.html to write your own revision guide. Give each topic its own document, and try and condense each subtopic to 5/6 points.

3. Go back to the long answer questions, and section them into different topics. And paste them into the bottom of the relevant topic's revision document.

4. Go to the answer schemes and give the write 4/5 points as an answer to all the long answer questions.

Reply 7

rose27

OP

Ekpyrotic

Ok, you're misunderstanding the material here. When's the exam?

tuesday- 27th

Reply 8

rose27

OP

Ekpyrotic

My advice:

1. Go through all the exam papers and grab the long answer questions. Just paste them all into an empty document.

2. Use this website http://www.harmsy.freeuk.com/Alevelreq.html to write your own revision guide. Give each topic its own document, and try and condense each subtopic to 5/6 points.

3. Go back to the long answer questions, and section them into different topics. And paste them into the bottom of the relevant topic's revision document.

4. Go to the answer schemes and give the write 4/5 points as an answer to all the long answer questions.