Physics Answers

[onlyfknhuman]

YEAH THAT WAS P TO Q WAT THE FK

[pinchies]

Mao told me after the exam it was Q-P

Sorry Skullmaster, if Master Mao said it then it must be true! yay :-D
That one had me waay worried.

[champorado]

lacoste: it's just substitution. Easiest maths in year 12.

[pinchies]

@lacoste: The maths is nothing but times divide plus and subtract - and some manipulation of powers of 10, but thats about it -> nothing to stop you having fun in the crazy pracs.
Edit: Beaten to it. Well, I concur. :-D

[fkzbaby]

if P was at top, P - Q
clockwise i think that was :O

physics is easy
just gotta know what your doing =P

[champorado]

if it was clockwise, wouldn't it be Q to P? It asked the direction in the square, so wouldn't it start at point q and then go to p?

[fkzbaby]

shiit. then i put the wrong thing >=[

[dcc]

The question specifically asked for whether it was Q to P through the square coil.  The current was flowing clockwise, so it went for Q to P.

[BiG DaN]

Power
2. AB
3. 4 x 10^-3
4. 8 X 10^-5
5. B
6.D
7 2.8V
8 C
9 1.6 x 10 ^-6
10 Q to P (think its wrong)
11 48W
12 8V
13 8A (dunno bout this)
14 400 turns
15 0.17

Light
3 4.5
7 5x 10 ^-15 eV
8 2.4
9 0.036
10 3.03
11 arrow from n=4 to 2 with head at 2
12 97nm

SOUND
1. B
2. C (wrong its ment to be B)
3. B
4. C
5. B
6.B
7.B
8.C
9.C
10.C
11.A
12.A
13.D

can some1 tell me how many i got wrong?

[pinchies]

The question specifically asked for whether it was Q to P through the square coil.  The current was flowing clockwise, so it went for Q to P.

Thanks for that-> it was kind of key to getting it correct! It nearly tripped me up until I read it again. Unfortunately (not for them!) people who may have got lenz law wrong and also missed this may in fact get the question right.

[Nelle91]

I put P-Q, put i drew a diagram of current going clockwise in my explanation, ( i thought it was through the circle) would i get any marks?

[ilovevce]

Here are my answers. Can't remember all the questions in light and matter. Anyone care to tell me what they are and I'll be able to remember the answers.

Power
2. AB
3. 4 x 10^-3
4. 8 X 10^-5
5. B (modulus sine graph)
6. D (normal sine graph)
7. 2.83V
8. C
9 1.6 x 10 ^-6
10. Q to P - magnetic flux into page decreases, so opposing magnetic field, produced by the current, goes into the page
    to counteract this. Using right-hand rule, current flows anticlockwise. Since it specified direction IN THE SQUARE LOOP,   this is from Q to P
11. 48W
12. 9V - V(floodlight) = V(total) x R(floodlight)/R(total) = 12 x (3/4) = 9V
13. 4.8A - I/R(eff) = 1/3 + 1/3 = 1/1.5  >> R(eff) = 1.5ohm >> R(total) = 1.0 + 1.5 = 2.5ohm >> I = V/R = 12/2.5 = 4.8A
14. 400 turns
15. 0.17

Light
1. Incandscent globe > free electrons in conduction band are energized by electrical energy, and they move/vibrate. These vibrations involve many energy transitions, and a continuous spectrum is produced.
2. Incandescent globe - continuous spectrum. Mercury vapour lamp - discrete spectrum
3. Path difference = 4.5cm
4. Minima and maxima spread out, X moves away from W. Using triangle geometry, as base gets smaller, ratio of hypotenuse/other side becomes smaller. Hence distance travelled must be greater for the same path difference.
5. Linear graph of KEmax v. frequency > easiest way is to use eV as units
6. 2.50eV
7. 5.0 x 10^-15 eVs
8. ?
9. 0.036nm
10. ?
11. Arrow from n=4 to n=2 with pointing towards n=2
12. 97nm

SOUND
1. B
2. B
3. B
4. C
5. B
6. B
7. B
8. C
9. C
10. C
11. A
12. B
13. D

[JackOfSpades]

doubt it nelle... sorry

[dcc]

The question specifically asked for whether it was Q to P through the square coil.  The current was flowing clockwise, so it went for Q to P.

Thanks for that-> it was kind of key to getting it correct! It nearly tripped me up until I read it again. Unfortunately (not for them!) people who may have got lenz law wrong and also missed this may in fact get the question right.

nps samuel.

[Nelle91]

Does anyone have a link to the exam