Year 12s: what will be the first way you research your future options? >>

AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

Scroll to see replies

Hello guys , for the charged particle to move in circular motion, was it at right angle to electric and magnetic fields which are perpendicular, or just magnetic , this confused me!

Reply 4681

MSB47

Original post by JAW-97

Maybe, wasn't it initial charge though? The charge would always be changing, so don't see how it could be area under the graph?

Im sure it was total charge thats represented with area inder graph because its the same as Q=It

Posted from TSR Mobile

Reply 4682

Lau14

Original post by CD223

Are people in agreement with my unofficial mark scheme (see first post) for the multiple choice? Now just need to fill out the written.

Posted from TSR Mobile

Question... 15, I think? Should also have an "Upwards" with it, there were two columns and you had to pick the right row.

Reply 4683

RemainSilent

for the angle ques i got it wromg however converted radians to degrees; would i get a mark ?

Reply 4684

StarvingAutist

Original post by JizzaStanger

But it could theoretically happen in a shorter time.

Yeah, but I think they meant you to interpret it as taking the same time, hence them saying "instantly" or words to that effect.

Reply 4685

Sbarron

Original post by imyimy

DAADABCDCABCDCBCCDBABACBC
no idea how ive done therethis is what i remember
forced vibrations are when theres vibrations that are forced that aren't at its natural freqnency with a phase difference and different amplitude
resonance is when the driving frequency=natural frequency causes oscillations large amplitude pi/2 phase diff.
coloumbs law- proportional to product of magnitudes of charges, inversely proportional to square of separation..
27.8 nC i put 28nc approx=to 30nc
4.5x10 to something J
1600
1.4m
some energy converted to chemical energy or sound energy
not 100% efficient in transferring to potential energy
the iron core in the coil causes changing magnetic flux induces an emf, which causes a current. low resistance so higher current.... etc
0.06 Wb turns
0.12V
130 degrees
i got tension as 15 which is def wrong.
2 revolutions
6 marker
constant speed- however changing direction means changing velocity- acceleration-f=ma f=mv2/r... opposite equal forces, resolve tension horizontally=centripetal force and vertically=mg.. not horizontal due to weight. (idk whether this is right)

Do you remember how many marks for each question please??

Reply 4686

Kennethm

21. was A not 0.5 x 0.5 since one side wasnt perpendicular to the magnetic field...

Reply 4687

CD223

Original post by Lau14

Question... 15, I think? Should also have an "Upwards" with it, there were two columns and you had to pick the right row.

True!

Posted from TSR Mobile

Reply 4688

khiz

http://www.bbc.co.uk/news/education-33094306

Lmaooo I knew it!!

Reply 4689

CD223

Original post by Kennethm

21. was A not 0.5 x 0.5 since one side wasnt perpendicular to the magnetic field...

Sorry could you explain? The couple I believe is largest when there is the greatest distance between sides. 0.5L was the greatest distance.

Posted from TSR Mobile

Reply 4690

a.a.k

Is there a mark scheme

Posted from TSR Mobile

Reply 4691

000alex

Did the induction question say that resistance was increased or decreased?

Reply 4692

Kennethm

Original post by CD223

Sorry could you explain? The couple I believe is largest when there is the greatest distance between sides. 0.5L was the greatest distance.

Posted from TSR Mobile

Oh k I'm wrong then lol. I just picked the side with the largest length that was perpendicular to the magnetic field. didn't really consider anything else.

Looks like its 20/25 for me - not too shabby I suppose - guessing that's the average A grade MC mark.

Reply 4693

khiz

The resistor question was worded wrongly!!!

http://www.bbc.co.uk/news/education-33094306

Reply 4694

CD223

Can someone either link me to an existing post with written answers, or type up their answers to the written ones so we can debate? I'll add it to the mark scheme in the first post after.

I'll also attempt to remember my answers...

Posted from TSR Mobile

Reply 4695

000alex

Do you think AQA will get rid of the mark for the graph intercept or will they only compensate those who used 300,000 ohms?

Reply 4696

chizz1889

Original post by eshaq

Why are you using the 30nC and not the 60nC charge? I know most people got an answer around 4.5 x 1^(k) (dont remember the power) but i got the double of that answer.

I used 60nC/4pie0 (5-2) rather than 30nC/4pie (5-2)

Then times it by the 60nC charge to find work done.