For those asking, we need to be able to define the AU, the parsec and the lightyear, but only "remember" (since the light year is in the formulae booklet) the distances of the parsec and the light year.

Reply 1205

stargazer678

Original post by chem@uni

June 2013 Q10

thanks! I've seen that, i mean with all the other stuff drawn in too

Reply 1206

chem@uni

9

Sorry I meant they have completed the drawing in the MS

Original post by stargazer678

thanks! I've seen that, i mean with all the other stuff drawn in too

Reply 1207

chem@uni

9

Original post by SH0405

For those asking, we need to be able to define the AU, the parsec and the lightyear, but only "remember" (since the light year is in the formulae booklet) the distances of the parsec and the light year.

What he meant to say was all we have to remember is AU and parsec

Think you got confused

Reply 1208

Faded-Pi

3

My question got lost in the stream of replies last time, but if you're working out the force on a coil in a magnetic field. Do you use F=BI(2*L) since both lengths would be in the field? Thanks.

Reply 1209

stargazer678

Original post by chem@uni

Sorry I meant they have completed the drawing in the MS

ok great! thanks!!

Reply 1210

chem@uni

9

Original post by Faded-Pi

My question got lost in the stream of replies last time, but if you're working out the force on a coil in a magnetic field. Do you use F=BI(2*L) since both lengths would be in the field? Thanks.

A coil is just one length of wire

Imagine a spring you wouldnt argue that was two lengths of wire just because it was wrapped up

Reply 1211

nothepreacher

18

Original post by ETRC

pair production is highest- they involve high energy x-rays being released

then its compton

photoelectrons from photoelectric have least energy

my brain hurts now from revising for 7 hours with a 30min break -.-

Awww take a rest! I still need to do a lot though :frown:

And I am screwed as I don't remember much of AS stuff

Reply 1212

Faded-Pi

3

Original post by chem@uni

A coil is just one length of wire

Imagine a spring you wouldnt argue that was two lengths of wire just because it was wrapped up

I meant more of a generator coil within a magnetic field, where a force acts on one side upwards and the other downwards. Wondering if the force therefore required using the two lengths in the formula. Might not, I dunno.

Reply 1213

chem@uni

9

Original post by Faded-Pi

I meant more of a generator coil within a magnetic field, where a force acts on one side upwards and the other downwards. Wondering if the force therefore required using the two lengths in the formula. Might not, I dunno.

No once again still one length of wire no you dont double

Reply 1214

fnatic NateDestiel

18

Original post by chem@uni

Can someone explain how I got from
s-1 Hubbles constant to
kms-1 Mpc-1

very common question.

Reply 1215

Chung224

13

Original post by randlemcmurphy

If the resistance decreases shouldn't the time constant...?

yeah sorry you're right

Reply 1216

chem@uni

9

Original post by fnatic NateDestiel

very common question.

To which the answer is?

Reply 1217

buxtonarmy

6

Original post by Smug Life

Still on 2010?

Haven't finished 2010 yet mate.

Reply 1218

leroythelost

10

Hey how would guys say x-rays are produced?

How would it be different in a hospital machine because I have looked at two questions saying describe how x-rays are made and says in a hospital x-ray machine and the other one says an x-ray tube but the answers are different.

Reply 1219

jcwh97

2

Original post by chem@uni

To which the answer is?

To go from s^-1 to kms^-1 Mpc^-1 =

Take your value and multiply by 1000 and divide by 3.2x10^16 x 10^6

The answer in s^-1 will be roughly 2.0x10^-18 and in kms^-1 Mpc^-1 it will be about 65 - 70

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

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