Insight 08 Physics Solutions.

[Cthulhu]

Would someone [Mao] like to give us their solutions to the insight exam if they've done the exam?

[DiMmY]

Didn't you get the solutions with the exam? I have the solutions (I'm actually doing the exam atm...), can take photos of them and give them to you later if you like?

[Cthulhu]

Sure, that would be great, thanks.

[smachet]

correct me if im wrong:

AOS1
1. D
2. 0.10A
3. 0.0040T (Telsa)
4. [i actually got 0.16V]
    T=1/f=1/10. hence delta(t)=0.025s. subbing it into emf formula gave me 0.16V
5. 0.004N. Anticlockwise when viewed from top
6. A force would act perpendicular to the magnetic field and current. The coil would oscillate through 90 degrees since no commutator is present.
7. Allows current to connect and disconnect from coil at particular intervals. This allows current and hence force to switch directions each 180 degree turn. Hence torques act in same direction each 180 degrees, allowing coil to rotate.
8. B
9. C
10. 0.60W
11. 2.5mA
12. 25 turns
13. 240 ohms
14. 0.050 W
15. 11V
16. 3.93E-5 V
17. anticlockwise [bad question]

AOS2
1. The thermal vibration of electrons that lose energy as photons. The light produced is incoherant and ranges over a broad spectrum. Photons of many different frequencies are emitted in all (random) directions.
2. A
3. 4.1x10^(-7) m
4. 3.02eV
5. A
6. Photocurrent is affected by intensity of the light source, NOT kinetic energy of electrons. This is because by increasing intensity, prob of electrons absorbing photos is greater.
7. B
8. see q6
9. 2.07eV
10. 0.95V
11. pd of 0lambda gives constructive interference and a bright band at centre. light is in phase etc..
12. 2.4E-11 m
13. 7.0E-14 Hz

DS1: Synchrotron
2. 1.16T (Telsa)
3. Into page
4. 10.2 keV
5. 1.5E-19C
8. T T F

[DiMmY]

correct me if im wrong:

AOS1
1. D
2. 0.10A
3. 0.0040T (Telsa)
4. [i actually got 0.16V]
T=1/f=1/10. hence delta(t)=0.025s. subbing it into emf formula gave me 0.16V

5. 0.004N. Anticlockwise when viewed from top (?)
6. A force would act perpendicular to the magnetic field and current. The coil would oscillate through 90 degrees since no commutator is present.
7. Allows current to connect and disconnect from coil at particular intervals. This allows current and hence force to switch directions each 180 degree turn. Hence torques act in same direction each 180 degrees, allowing coil to rotate.
8. B
9. D
10. 0.60W
11. 2.5mA
12. 25 turns
13. 240 ohms
14. 0.050 W
15. 0.55 W
16. 3.93E-5 V
17. anticlockwise [bad question]

4. The answer is 1.6V... they for some reason use N = 500 (perhaps because of the 10Hz? :S)
6. Answer sheet says you have to mention it will STOP.
9. C
15. Is asking for VOLTAGE drop, not power. Answer is 11V
17. Clockwise.

[smachet]

Q4 insight stuffed up in that case (and 1.6V seemed too much anyway)
Q9 got it.. ill fixed it up now
Q15 oops.. i wrote that but copied the 1st part of my answer.. its fixed now
Q17 please explain..

[DiMmY]

Q17 please explain..

Directly from answer sheet:

"The correct answer is clockwise. From the teacher's point of view, the magnetic field towards the teacher would be increasing as the ring goes into the magnetic field. Lenz's law states that the ring will resist this change, therefore setting up a magnetic field towards the coil. To do this, it needs to produce a current clockwise."

I wrote anti-clockwise as my answer too *shrug*.

[DiMmY]

Follow the file names ladies - http://www.danielgphoto.com/vn

'scuse the crappy quality, darkish in my room and doing the photos quickly doesn't work well.

[Cthulhu]

4. The answer is 1.6V... they for some reason use N = 500 (perhaps because of the 10Hz? :S)

500 turns? But the question says there is only 50 Turns.

[DiMmY]

4. The answer is 1.6V... they for some reason use N = 500 (perhaps because of the 10Hz? :S)

500 turns? But the question says there is only 50 Turns.

Well, I was wondering that too, as I initially got .16V. Get to the answers and they use 500 x flux / .025.

Little disappointed - got 83% overall (doing sound as DS) on this, 86% yesterday on Neap. Need to study up electric power, where I'm losing nearly all my marks =/

Anyway, off to do Lisachem 2008.

[onlyfknhuman]

yeah its a misprint its either 500 turns or 100hertz so screw teh question dudes.

[smachet]

its a misprint.. get over it
everyone does it (especially vcaa 04 sample)

[DiMmY]

its a misprint.. get over it
everyone does it (especially vcaa 04 sample)

I think I saw about 3 misprints in the Neap 2008 solutions =/

h = 6.16x10^-34 eh...

[onlyfknhuman]

Yeah and their selling this to students for outrageous prices, and they dont even fuckn check their own answers fuckn pathetic.

[Cthulhu]

I redid questions 3-4 roughly 200 times just to make sure I wasn't doing the questions wrong and it was Insight. Fuck I hate that shit.