AQA PHYA4 ~ 13th June 2013 ~ A2 Physics

Original post by Jack93o

on a scale of 1 - 10

how sure are you that the answer is 'horizontal, BLV'?

...**** I'm getting paranoid

If i've got the details correct, magnetic field to the right? (or left, doesn't make a difference), the rod was perpendicular to the field from the side view which mean the current was, so i would rate 10 for horizontal, i'm fairly sure it was BLV but not 100% so 8 for that

Reply 762

Original post by Qwertish

Lower than normal, I think. Section A was a bit harder than normal, and loads of people would have got 1c or the peak emf one. QWC question was pretty straightforward though, so that might balance it out.

just to check, the 6 marker was question 4 wasn't it? (like, it wasn't 4a, 4b, etc)

Reply 763

cooldudeman

18

This is ridiculous. Jan13 was the hardest one ive ever done but it had the highest boundaries out of the ones in the past. In order of the latest ones, the full ums has been 63, 63, 62, 62, 62, 60, 62. Im guessing its gonna be 63 this time but what does everyone else think????

Posted from TSR Mobile

Reply 764

foximus

for the Dees question, work out velocity by:
mv^2/r = BQv
v = BQr/m and just used 0.48T and the radius they give with Q and m values for a proton

direction of magnetic field was into plane of the paper.

to work out the Pd between the two plates just did E = V/d with E being the breaking force thing.

with capacitance greater it was RC larger therefore greater time between sparks, but greater brightness as more charge can be stored so more energy stored.

for multiple choice:
- there is a couple on the coil (for the electric motor one)
- 3.6 for ratio of earth and moon radius or something
- 2mu for particle

(edited 10 years ago)

Reply 765

Original post by The H

If i've got the details correct, magnetic field to the right? (or left, doesn't make a difference), the rod was perpendicular to the field from the side view which mean the current was, so i would rate 10 for horizontal, i'm fairly sure it was BLV but not 100% so 8 for that

I definitely remember the magnetic field was shown by an arrow to the right

Reply 766

Original post by cooldudeman

This is ridiculous. Jan13 was the hardest one ive ever done but it had the highest boundaries out of the ones in the past. In order of the latest ones, the full ums has been 63, 63, 62, 62, 62, 60, 62. Im guessing its gonna be 63 this time but what does everyone else think????

Posted from TSR Mobile

ha....thats what I thought as well when I was doing the past papers

couldn't believe the boundary was higher than the easier papers like the ones in 2010 (and one in 2011 I think)

Reply 767

flashbackto1999

Original post by foximus

for the Dees question, work out velocity by:
mv^2/r = BQv
v = BQr/m and just used 0.48T and the radius they give with Q and m values for a proton

direction of magnetic field was into plane of the paper.

to work out the Pd between the two plates just did E = V/d with E being the breaking force thing.

with capacitance greater it was RC larger therefore greater time between sparks, but greater brightness as more charge can be stored so more energy stored.

for multiple choice:
- there is a couple on the coil (for the electric motor one)
- 3.6 for ratio of earth and moon radius or something
- 2mu for particle

no there was an equal and opposite force in either side of the coil.

Reply 768

S1L3NTPR3Y

13

Did anyone else get 3.5*10 to the something for the capacitance question? And also can anyone else remember the other parts of the question, it got brighter as there was more energy?

Reply 769

The H

Original post by Jack93o

I definitely remember the magnetic field was shown by an arrow to the right

BLV is the area of flux cut per second, equivalent of BA, so yeah i'm confident with the answer

Reply 770

Anythingoo1

13

I really hope I improved on my January score, I'd be surprised if I didn't as in January I couldn't answer half the questions and ended up with a D. I actually managed to do all the questions in this paper (not saying I got them all right by any means, but it should still be an improvement)

Screwed up the ratio one with the 1st question, did the 1.9/2.0 bit and 20 x 2 but forgot to minus by 2 to account for the first oscillation! Oh well hopefully a method mark for the ratio bit :smile:

Just blanked out at the 2 situations when particle is stationery question, now I think about it is so obvious.

Hopefully that B will be coming my way on August 16th! :biggrin:

Reply 771

marcolliwright

Original post by The H

I put 8F ( If i'm thinking of the right question) and I also guessed the Mars one, but I think I should have put 25MJ

I'm fairly sure the Mars question was -13MJ? Because...

The Earth has -63MJ and for Mars the mass is 10 times smaller so that would become -6.3MJ. However the diameter (and therefore the radius) is twice as small so you're dividing by a number twice as small (as potential is proportional to 1/R) so you multiply by 2 which gives you -12.6 = -13MJ (2sf)

Reply 772

cottonsocks0_0

Original post by Lay-Z

I thought it was really good, only question I didn't really like was the brightness one.. if only I did better in my isa's might have been able to get A* :sigh:

Posted from TSR Mobile

that one is so hard.the unit of the brightness is W m-2.
Thus B=IV/area, IV is unchanged , area is increased, thus the brightness is decreased. i just realized that last second!!!i even thought brightness=IV!!!
i really think none can get it!!!!

Reply 773

Original post by cooldudeman

This is ridiculous. Jan13 was the hardest one ive ever done but it had the highest boundaries out of the ones in the past. In order of the latest ones, the full ums has been 63, 63, 62, 62, 62, 60, 62. Im guessing its gonna be 63 this time but what does everyone else think????

Posted from TSR Mobile

wait, I thought jan this year had full ums at 65 :s-smilie:

#

edit, you're right

(edited 10 years ago)

Reply 774

The H