You are Here: Home >< Physics

# OCR Physics A Exam - G482 Electrons, Waves, Photons [09/06/16]

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
1. (Original post by Tyler'sD)
Good paper for me, the ones im not sure if i got was the why the 3ohm resistor and i dont know if i proved it was 30mA correctly in the LED, i worked out the LED resistance then worked out the voltage in the resistor then worked out the current, it that what everyone else did??
I found p.d. across the LED, resistance from graph at 30mA, then subbed into v=IR, showing current is 30mA.. got resistance to be 100 ohms
2. Generally I thought the paper was ok. Stationary wave one I thought was alright but that first question with A1 and A2. I had no idea on! Wasn't sure what was going on. Didnt like the fuse one either because I couldn't tel what was in series and what was in parallel with the 8. A few bits here and there were rank too but generally ok.
3. (Original post by RBoss)
I found p.d. across the LED, resistance from graph at 30mA, then subbed into v=IR, showing current is 30mA.. got resistance to be 100 ohms
Thats what i did
4. (Original post by RBoss)
I found p.d. across the LED, resistance from graph at 30mA, then subbed into v=IR, showing current is 30mA.. got resistance to be 100 ohms
yeah i got 100 too
5. (Original post by Hasib98)
Thats what i did
Yeh same.
6. What did everyone put for the fuse question? I put 50mA because I worked out the total current of the circuit to be like 15mA. Seems way too low though....
7. Did anyone get the current to be 89/90 mA, so fuse value was 500mA?
8. (Original post by RBoss)
Did anyone get the current to be 89/90 mA, so fuse value was 500mA?
I said the fuse value was 50mA because my current was around 30mA.
9. (Original post by NickLCFC)
What did everyone put for the fuse question? I put 50mA because I worked out the total current of the circuit to be like 15mA. Seems way too low though....
I have no idea if I got it right but I got the current to be about 20 mA so also put 50mA
10. Definitely think it was fine, though unusual. I know I messed up the harmonics hard, thankfully that wasn't toooo many marks, and I am very confident I got at least a part of it right... (the speed part). I think most of it wasn't too hard, reckon I did well, an A or a B I think. Definitely much better than last year is any case.
11. (Original post by NickLCFC)
What did everyone put for the fuse question? I put 50mA because I worked out the total current of the circuit to be like 15mA. Seems way too low though....
From what I remember, the resistances of LED and resistor in series was 167 ohms, so total resistance was 55.6..., so I = V/R = 5/55.666 = 90mA
12. (Original post by RBoss)
From what I remember, the resistances of LED and resistor in series was 167 ohms, so total resistance was 55.6..., so I = V/R = 5/55.666 = 90mA
Didn't they arrange the 100ohms LEDs and 67ohms resistors in parallel though? From what I can remember, there was 7 parallel 'arms' of a resistor and LED in series
13. (Original post by Tyler'sD)
yeah i got 100 too
For the eV = 1/2 mv^2 question, I did eV = h / mv instead, do you think I will get any kind of marks?
14. (Original post by NickLCFC)
Didn't they arrange the 100ohms LEDs and 67ohms resistors in parallel though? From what I can remember, there was 7 parallel 'arms' of a resistor and LED in series
Snap yeah there would have been 7 LED's in parallel, with one resistor, and then 3 lots of the total resistance in parallel to make the 3 digit display
15. Resistance was 67/3 and V was given as 5 so do I=v/r and i was ~220mA therefore i selected 500mA anyone else do this?
16. (Original post by Abb97)
Resistance was 67/3 and V was given as 5 so do I=v/r and i was ~220mA therefore i selected 500mA anyone else do this?
I think you're right. I've just had another go at it from how I can remember the question and got the same answer as you
17. Did anyone get 340ms-1 for the wave speed? And what was the fundamental frequency was that just 512hz i didnt know what to do for that 1 mark??
18. Yh i looked at that question carefully pretty sure its right
(Original post by NickLCFC)
I think you're right. I've just had another go at it from how I can remember the question and got the same answer as you
19. (Original post by Abb97)
Did anyone get 340ms-1 for the wave speed? And what was the fundamental frequency was that just 512hz i didnt know what to do for that 1 mark??
Yeah I got something like 340, and I got 256Hz for the fundamental frequency (512/2)
20. (Original post by Abb97)
Did anyone get 340ms-1 for the wave speed? And what was the fundamental frequency was that just 512hz i didnt know what to do for that 1 mark??
Fundamental frequency would have been 3 * 512 I think.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: June 12, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources