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# Edexcel A2 Physics Unit 5 'Physics from Creation to Collapse' watch

Are you going to buy it for one day?
9780340888070 - Tim Akrill
9781408206089 - Miles Hudson

The files there are Word, I think you know that.
What's the problem with them?
yeahh, Ill give them to my school library when im done, they need useful books!

and i know its word, it just wont open =/
2. I don't understand the process of using standard candles to determine distances, can someone briefly explain..
3. Teacher at school say you can use a GM tube with a thin mica window to detect alpha radiation. We have done this a number of times in experiments and definatly works. The teacher says that alpa radiation can penitrate a thin mica window.

However...

The book says that you can not detect alpha radiation with a gm tube as it cannot penitrate the thin mica window.

Any help on this....?
4. listen to the books, ive read that in more than one book, alpha cannot pass through mica window of the GM tube, alphas range in air is only a few centimeter
tbh i got no clue how your exp at school worked
5. (Original post by skypistol)
I don't understand the process of using standard candles to determine distances, can someone briefly explain..
cepheid variables are standard candles.Cepheid variables are stars in which is luminosity is periodic.so first,measure the time period for the luminosity of the star.from the time period the luminosity can found using leavitts L-T graph. measure the intensity from the star at earth.use I=L/4(pi)d^2 to measure distance d
6. (Original post by Bulmer)
Teacher at school say you can use a GM tube with a thin mica window to detect alpha radiation. We have done this a number of times in experiments and definatly works. The teacher says that alpa radiation can penitrate a thin mica window.

However...

The book says that you can not detect alpha radiation with a gm tube as it cannot penitrate the thin mica window.

Any help on this....?
No it cannot.it only last few centimetres in air
Your experiment might have worked only if the gm-tube was very very close to the emitter like some millimetres apart
7. http://cid-5432f573d3fc3f5a.office.l...0decay%20Q.doc

How would I do Q4-part (a) and (d) please?
8. (Original post by unamed)
according to one of the questions I was doing, yes.

In other news, I've lost the motivation to revise for this, so, does anyone have a question?
Which one of these is more stable:
Carbon-12or Copper-56 (which happens to be radioactive)?
Binding Energy per Nucleon.

(Original post by Bulmer)
Teacher at school say you can use a GM tube with a thin mica window to detect alpha radiation. We have done this a number of times in experiments and definatly works. The teacher says that alpa radiation can penitrate a thin mica window.

However...

The book says that you can not detect alpha radiation with a gm tube as it cannot penitrate the thin mica window.

Any help on this....?
As long as I know, alpha particles cannot be detected by G-M tube, because they cannot penetrate thin mica window..
Alpha particles can be stopped with a sheet of paper (or skin).

(Original post by skypistol)
I don't understand the process of using standard candles to determine distances, can someone briefly explain..
We can measure radiation Flux (F) here on Earth.
And as we know their Luminosity (L), using F = L/4пd2, distance (d) to those standard candles can be calculated.
9. (Original post by nnamdi)
cepheid variables are standard candles.Cepheid variables are stars in which is luminosity is periodic.so first,measure the time period for the luminosity of the star.from the time period the luminosity can found using leavitts L-T graph. measure the intensity from the star at earth.use I=L/4(pi)d^2 to measure distance d
ok there are two stars each one with a different peroid, is the star with longer peroid further away?
10. (Original post by skypistol)
I don't understand the process of using standard candles to determine distances, can someone briefly explain..
Basically, the luminosity and flux of the stars/supernovae being used as standard candles can be found without having to use distances etc. Therefore, if you want to find out how far another star with the same luminosity as a standard candle, you stick it into:

F= L/4pi.d2

and get d.
And hence, you have used the 'standard candle' method.
11. DO we have to know Earth's radius, distance from Sun ?
Coz Questino 18 b)i) ... needs us to know that sort of stuff.
Which one of these is more stable:
Carbon-12or Copper-56 (which happens to be radioactive)?
Binding Energy per Nucleon.

Yep, that one.
Quick question regarding that graph - the ones with the lowest binding energies per nucleon
Now, I'm confused. Iron-56 is considered highly stable, yes? < then why is U-235 considerably high as well? Is it because it's per nucleon - and it has more nucleons, hence making it less stable in reality?
Argh. Very confused over this now.
Which one of these is more stable:
Carbon-12or Copper-56 (which happens to be radioactive)?
Binding Energy per Nucleon.

As long as I know, alpha particles cannot be detected by G-M tube, because they cannot penetrate thin mica window..

We can measure radiation Flux (F) here on Earth.
And as we know their Luminosity (L), using F = L/4пd2, distance (d) to those standard candles can be calculated.
how do we know their luminosity?!
14. (Original post by skypistol)
ok there are two stars each one with a different peroid, is the star with longer peroid further away?
Not really.
Longer period means higher luminosity (total power output).
So it might be just larger/hotter.
You should then measure radiation Flux, and from these two value calculate the distance.
15. (Original post by unamed)
Basically, the luminosity and flux of the stars/supernovae being used as standard candles can be found without having to use distances etc. Therefore, if you want to find out how far another star with the same luminosity as a standard candle, you stick it into:

F= L/4pi.d2

and get d.
And hence, you have used the 'standard candle' method.
im sorry im not getting you :/
16. (Original post by kappleberry)
http://cid-5432f573d3fc3f5a.office.l...0decay%20Q.doc

How would I do Q4 please?
a)55/7.65*10^-13 = 7.19*10^13

b)ln(2)/(1620*365*24*3600)= 1.36*10^-11

c)7.19*10^13/1.36*10^-11 = 5.3*10^24

d)1.411*10^46
Not really.
Longer period means higher luminosity (total power output).
So it might be just larger/hotter.
You should then measure radiation Flux, and from these two value calculate the distance.
how do u know that a longer period means higher luminosity ?
18. (Original post by unamed)
Yep, that one.
Quick question regarding that graph - the ones with the lowest binding energies per nucleon
Now, I'm confused. Iron-56 is considered highly stable, yes? < then why is U-235 considerably high as well? Is it because it's per nucleon - and it has more nucleons, hence making it less stable in reality?
Argh. Very confused over this now.
Hehe.. sorry for confusing you.
You know that the value of binding energy is calculated from ([mass of nucleons on their own] - [mass of these nucleons in the nucleus])/[number of those nucleons].
And this happens to be the way it is on that curve.
19. (Original post by nnamdi)
a)55/7.65*10^-13 = 7.19*10^13

b)ln(2)/(1620*365*24*3600)= 1.36*10^-11

c)7.19*10^13/1.36*10^-11 = 5.3*10^24

d)1.411*10^46
thank you buttt...I dont get the method of part a =/
20. (Original post by skypistol)
how do u know that a longer period means higher luminosity ?
Their luminosity is directly related to their period of variation.
The longer the pulsation period, the more luminous the star.
http://en.wikipedia.org/wiki/Variable_star
But I think we're not required to know that.

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