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PHYA1 - Physics Unit 1 Exam - 24th May 2011

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guys, how do you work out specific charge for an ion?
Reply 61
Avatar for Aarynn
Aarynn
Original post by Notsocleverstudent
guys, how do you work out specific charge for an ion?


0 + #of electrons gained x (-1.6x10^-19)
# of nucleons x (1.67x10-27)

I'm pretty sure that's it, obviously if you lost electrons the top value would be positive (losing one electron is gaining -1 electrons). Someone please correct me if i'm wrong.
Original post by jilebinator
on the jan 2011 paper question 6 (d) (i) and (ii) should'nt it be the otherway around. i though the current is the same in series and split in parrallel... :confused:


nope because in series, you'll have two filaments so the resistance will be DOUBLE and hence the current will be less. while when they're in parallel, the total resistance will be less so the current passing through will be higher.

idk if I explained that well, sorry.
Reply 63
Avatar for Porkk
Porkk
Original post by Aarynn
0 + #of electrons gained x (-1.6x10^-19)
# of nucleons x (1.67x10-27)


why 0 + ? o.O
Reply 64
Avatar for Aarynn
Aarynn
Original post by Porkk
why 0 + ? o.O


Don't know XD Not necessary but it still works. Good point :smile:
Reply 65
Avatar for JAEGER.
JAEGER.
need some help with oscilloscopes any one!
Original post by JAEGER.
need some help with oscilloscopes any one!


What about them?
They're basically just glorified voltmeters, and the trace is made by an electron beam moving across the screen.
- Time base controls how fast the beam is moved, and the vertical heigh of the trace shows the input voltage.
- The typical wave pattern shows AC current, obviously - DC would just be a straight line.
- Distance between peaks = time period, and frequency = 1/time period
- Peak voltage = the highest voltage = half the total maximum height, i.e. from the 0 line up to a peak but not from a trough to a peak.
- An AC supply with a peak voltage of 2V will be below 2V for most of the time, so its power output won't be as high as a 2V DC supply.
- rms Voltage is used to average the AC voltage, as the positive and negative values will cancel each other out.
- rms Voltage = the peak voltage divided by root2.
- rms Current = the same.
Power = Vrms x Irms
- Doesn't matter for resistance as peak values will produce the same answer.
(edited 12 years ago)
I know it's like 9 hours til the exam, but if anyone has specific questions on stuff please feel free to email me at [email protected] or even add me on msn, it's useful revision for me!
(edited 12 years ago)
Reply 68
Avatar for ktron
ktron
7
What happens to the emf of cells connected in parallel? so like this:

consider // as one cell.

____//_____
|___//_____|
|___//_____|

Erm lets say the emf of the first one at the top is 2V, then 3V and the bottom one 5V. What is the overall emf of across cells?
(edited 12 years ago)
Original post by kalp
What happens to the emf of cells connected in parallel? so like this:

consider // as one cell.

____//_____
|___//_____|
|___//_____|

Erm lets say the emf of the first one at the top is 2V, then 3V and the bottom one 5V. What is the overall emf of across cells?


Treat it the same as potential difference(voltage)

So it would be the p.d through the source when no current flows sooooo

You wouldnt get 3 different values for voltage anyway, only 1 since potential difference will stay the same
Reply 70
Avatar for beelz
beelz
How did people find it?
Most of it was OK I thought except no one had ever taught me about electron capture :\
Reply 71
Avatar for tomo30
tomo30
From all of us a CH, WE'VE FAILED!
Reply 72
Avatar for beelz
beelz
Grade boundary thoughts?
50/70 for an A?
Original post by beelz
Grade boundary thoughts?
50/70 for an A?


It was an easy paper, so I think higher than that for an A. Possibly 56/80.
Reply 74
Avatar for beelz
beelz
Original post by FallenProject
It was an easy paper, so I think higher than that for an A. Possibly 56/80.


It would never be that high, and I thought it was no harder or easier than most past papers, of which the grade boundaries range from 50-53.
(edited 12 years ago)
Yes, you could do that. The AS syllabus is fairly easy. Experiment details are in the AS AQA textbook, as well as the ISA stuff (formulae to learn) which is in the back.
could someone post up the answers, or what they got for this paper? if anyone has the original paper, that would be useful too.

i didnt think it was too bad, 51/70 for an A maybe. hopefully its lower than that.
Original post by beelz
It would never be that high, and I thought it was no harder or easier than most past papers, of which the grade boundaries range from 50-53.


I'll take your word for it. This is the first time I've actually revised for it, so that could be why I think it was easier than the previous one.
Reply 78
Avatar for Mr XcX
Mr XcX
15
I am really worried cause I found it good.

That probably means I have failed, lol.

The last electricty question was hard.
Reply 79
Avatar for beelz
beelz
What did people get for the electricity questions?
I got 1.33 Amps for the current through that resistor, and then 2 Volts across that resistor in parallel (with another resistor beside it), is that what other people got?

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