OCR Physics A G485 - Frontiers of Physics - 18th June 2015 Watch

I Persia I
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#1461
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#1461
Do we need to remember the Hubble constant? I can't find it in the formula booklet. Also can someone please explain how to convert it from its original form to SI units, I know it involves the conversion of parsecs but it;'d help thanks.
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Tiwa
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#1462
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(Original post by seizetoday)
Cheers.
No problem! All the best for tomorrow.
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nothepreacher
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#1463
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#1463
(Original post by Elcor)
Don't worry about Helium because it's only one of quite a few marking points your allowed, and I don't understand it either.

Intensifier converts 1 X ray photon into many visible light photons (the X rays would otherwise mainly pass through the photographic film so this reduces the dose)
Or in a gamma camera, scintillator converts one gamma photon into many visible photons
Thank you! And good night all! Get some sleep. You are all smarty pants, and have worked hard, and you're going to be fine!
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Jim997
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#1464
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#1464
(Original post by I Persia I)
Do we need to remember the Hubble constant? I can't find it in the formula booklet. Also can someone please explain how to convert it from its original form to SI units, I know it involves the conversion of parsecs but it;'d help thanks.
No we don't. It's around 65 kms-1mpc-1 ...

So do 65 times ten to the 3/ 3.1 times ten to the 22
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Tiwa
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#1465
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#1465
(Original post by I Persia I)
Do we need to remember the Hubble constant? I can't find it in the formula booklet.
Nope. Either they'll give it to you or you'll have to work it out as there is no definite value of of the Hubble constant. It's believed to be between  50kms^-^1Mpc^-^1 and  100kms^-^1Mpc^-^1 .
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seizetoday
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#1466
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#1466
(Original post by I Persia I)
Do we need to remember the Hubble constant? I can't find it in the formula booklet. Also can someone please explain how to convert it from its original form to SI units, I know it involves the conversion of parsecs but it;'d help thanks.
Impossible to get an accurate Hubble constant. You usually work it out or get it given to you. To convert it into SI units is self explanatory
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seizetoday
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#1467
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#1467
(Original post by Tiwa)
No problem! All the best for tomorrow.
Yes! Thank you, you aswell
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I Persia I
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#1468
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#1468
(Original post by Jim997)
No we don't. It's around 65 kms-1mpc-1 ...

So do 65 times ten to the 3/ 3.1 times ten to the 22
(Original post by Tiwa)
Nope. Either they'll give it to you or you'll have to work it out as there is no definite value of of the Hubble constant. It's believed to be between  50kms^-^1Mpc^-^1 and  100kms^-^1Mpc^-^1 .
(Original post by seizetoday)
Impossible to get an accurate Hubble constant. You usually work it out or get it given to you. To convert it into SI units is self explanatory
Rep for y'all for being so smart and also being awake to help me .
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Tiwa
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#1469
(Original post by I Persia I)
Rep for y'all for being so smart and also being awake to help me .
All the best for tomorrow!
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sarcastic-sal
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#1470
(Original post by Jmw123)
In these formulas with the activity ones as well, when can and should I ignore the first bit e.g. I=I0 and just work out e to the power of the two things in this case ux, its in a lot of topics and I don't understand how you can do this.
Sometimes you will be given the fraction or percentage of the initial activity or initial no of nuclei or initial intensity etc. If for example the question was 'at a depth of 2cm, the intensity of ultrasound is 11% of the initial intensity, calculate the attenuation coefficient' they have given you I/Io in disguise - as here, I/Io = 11/100. You can then just manipulate the expression using logs to find mu.
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I Persia I
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#1471
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(Original post by Tiwa)
All the best for tomorrow!
Cheers buddy you too!
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leroythelost
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#1472
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#1472
How do you define plasma?
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Tiwa
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#1473
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#1473
I ought to sleep now. All the best everyone.
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Raizel
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#1474
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#1474
(Original post by sagar448)
Guys why is the universe not infinite why was olber wrong? PLEASE HELP!
Olber's paradox is that, if the universe was infinite and static, then every line of sight would end on a star meaning that if you looked at the night sky it would just be bright because everywhere you look you will end up looking at a star, but look out side bro that's not the case, which means that the universe is not infinite and not static/homogeneous
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I Persia I
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(Original post by Raizel)
Olber's paradox is that, if the universe was infinite and static, then every line of sight would end on a star meaning that if you looked at the night sky it would just be bright because everywhere you look you will end up looking at a star, but look out side bro that's not the case, which means that the universe is not infinite and not static/homogeneous
:rofl: :rofl: :rofl:

We're Physics students bro, what is an outside?
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Raizel
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#1476
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#1476
(Original post by Tiwa)
I ought to sleep now. All the best everyone.
u2 bro, lets ace this madness
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Smug Life
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#1477
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#1477
Anyone else doing all-nighter? Gonna do 8 past papers tonight.
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Raizel
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#1478
(Original post by I Persia I)
:rofl: :rofl: :rofl:

We're Physics students bro, what is an outside?
Lool imagine if I put that on the paper, do you reckon I would get the full marks?
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Joseph.S
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#1479
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#1479
What is the average UMS needed for an A in this paper?
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leroythelost
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#1480
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#1480
(Original post by Smug Life)
Anyone else doing all-nighter? Gonna do 8 past papers tonight.
WTF don't do that, unless you have done like zero revision. I think sleep is more important
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