Sorry habosh, I didn't expect that it could have something similar, but it was. Anyway, it's not exactly the same.
- 1st one, I was confused when I calculate the mass ... Dan, I know it should be easy, I thought I did it in the wrong way. The other parts were ok.
- 2nd one, I found it was quite straightforward, just take the readings as they ask ...
- 3nd one, abit tough, but finally I found the way out :smile:

Reply 5

Imaad

it was so like yesterday's

Reply 6

nas7232

****!

i could of easily got a high A, i put the oscilloscope in series [omfg, i revised that set up so many times :angry:

], i measured L wrong, i had to guess the value at the end because of the stupid mistake.

Everything else i did good on i think may of messed up the inverse square law aswell

probs got 72% :mad:

Reply 7

Sparkling_Jules

So the oscilloscope went in parallel?! I'm glad I changed it now!

My inverse square was more of a straight inverse according to the values I got... oh dear!

Did seem a lot easier than some of the past papers.

Reply 8

Zany

What did you guys draw for the graph? How did it support the equation?

How did u say e = 1/r? Could you do value of e1/value of e2 = ........ do the same for 1/r and find percentage uncertainty?

(For a friend, did mine yesterday and screwed it up :p:

)

Reply 9

nas7232

i thought the question said inverse square law

:mad:

oh for **** sake lol. I said it did support the inverse square law and referred to E = k (Qq/r^2)
in this case E = k 1/ r^2

For r=2.0 cm, i drew a tangent, the gradient = E ~ 40Vm^-1
Therefore, inverse square law existed on small values of r, however for larger values of r the inverse square law was less pronounced.

Hope i get a leanent examiner so they can see that i mean E is proportonal to 1/r is not true.

Last question i plotted X vs 1/ 2pi f
1/C = gradient
cuts through the origin

Reply 10

Zany

She plotted an ln graph so thats clearly wrong! ~What did everyone else do for the E q?

How did you guys find the mass of the ruler?

Reply 11

sequence123

For the last graph i did X against 1/f, which led to a straight line through the origin

my ruler mass was approx 50 grams

For the 2nd one it wasnt exactly inversely proportional, but very close, i think it was designed to be that way.

Reply 12

bassman

i got 59g for ruler
did u get kgm^2 for units of torque?
inverse law was arite exponential decay-like graph
graph of x against f straight line thru origin
frequency on oscilloscope 250hz
voltage on oscilloscope 4.4v

how did u draw the circuit for the osciloscop/sig gen with the specified equipment? did u connect osciloscope across the sig gen? how did u explain it ie what readigs etc?

Reply 13

wackojacko

Bloody easy exam, whats with that? Didn't even have to set up the circuit!! Amazing. Oh well, im not going to complain :biggrin:

Reply 14

john !!

my rukler was 70g.. I did an average between about 66 and 74. but thats probably cos the rulers varied that should be an accurate experiment with the knife edge.

got the gradient double at 2 to what it was at 4cm away from the central electrode, so I thought it was an exponential decay. which it shouldn't be. but hey I said it wasnt inversely proportional which should be correct.

Reply 15

john !!

bassman

voltage was 3V ? it was one and a half markings and it was 2 volt per marking?
I agree with everything else.. yep kg m^2 for the value of I.

drew a normal circuit, with the three things in series and CRO parallel to the capacitor...

Reply 16

VCVT17

Oh,
I did in part three as considering the oscilscope can product the signal of the current.... ???
I'm not sure to think about how to measure the current of the capacitor?
I used the discharge capacitor time for the calculate Ic...?
Firstly, I did completely wrong for the planning and have to ask my supervisor to get another paper...
I think I lost about 7 marks..
Does anyone suggest for me how to take the value of Current Ic?
Thank U very much...

Reply 17

smartguyhirz

bassman

i got voltage as 2.8, it was direct from the given graph.

Reply 18

sumitk87

nas7232

****!

i could of easily got a high A, i put the oscilloscope in series [omfg, i revised that set up so many times :angry:

], i measured L wrong, i had to guess the value at the end because of the stupid mistake.

Everything else i did good on i think may of messed up the inverse square law aswell

probs got 72% :mad:

wow thats quite accurate

Reply 19

smartguyhirz

u guys sure we have to use inverse square law in the 2nd part?? coz using the gradients at the required places, E = change in V/change in r and to test the E inversely proportional to r, E = k/r
so E (tangent at a given point) times the r at that point (eg 2 or 4), u'd get k approx the same for all the two values of r (2 and 4) and if incase u decide to take any other points, it'll work.