Edexcel Physics Unit 2 January 2012

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Yeh everyone seems to be getting that, I understand why now. Stupid mistake. However i did find the 6 marks question pretty straight forward, the one about ground state. This is what I can remember, tell me if it is right:
The ground state is the minimum energy an electron can have.
When a photon hits the electron, the electron absorbs the energy, and is then excited to a new energy level. The electron then falls down, and emits a photon.

I meant to say, after looking on here it may have been too big! I'd like to ask my teacher what he thinks about it.
I found the 6 mark question pretty straight forward too, and even did a lovely labelled diagram in the space below hahaha.
Yeah that seems right to me. I talked about what energy levels are as well (discrete and unique for every material) and described absorption and emission as well at the end. I wasn't sure exactly what to put so I just wrote everything I knew about it and filled the whole page

Reply 41

tazi123

Original post by britchick

**** should have talked about emission spectra swell... 1 mark was for english wasn't it?

Reply 42

britchick

Original post by tazi123

**** should have talked about emission spectra swell... 1 mark was for english wasn't it?

I believe so, yes. So if you used full sentences, in a logical order, with correct spelling, I assume you'd get a mark. :smile:

Reply 43

ThaChronic

After seeing your answers I've probably got about 45/80 :| done really ****

Reply 44

britchick

Original post by ThaChronic

After seeing your answers I've probably got about 45/80 :| done really ****

Lol! 45/80 is still most likely around a B! Don't worry I'm sure you've done fine :smile:

This was a re-sit for me... guess what I got last time?

(edited 12 years ago)

Reply 45

gcse_____

What about that tiger effect when visitors enter the zoo ?

Reply 46

britchick

Original post by gcse_____

What about that tiger effect when visitors enter the zoo ?

I said:

The name of the effect is diffraction.
Diffraction is the spreading out of a wave when the wave encounters a gap or obstacle (in this case an obstacle i.e. the hill).
Therefore the waves produced from the tiger diffract around the hill and spread out to the entrance of the zoo where they reach the visitors' ear at the entrance to the zoo.

(edited 12 years ago)

Reply 47

tazi123

Original post by gcse_____

What about that tiger effect when visitors enter the zoo ?

I put the wavelength of the infrasound was big, so it can diffract around hills, so the visitors can hear the tigress. However because the wavelength of light is very small, there is very little diffraction and so you cannot see the tigres.

Reply 48

britchick

Original post by tazi123

This is a very good answer

Edit: isn't there NO diffraction of light from the tiger around the hill, hence why you can't see it, rather than "very little diffraction"?

(edited 12 years ago)

Reply 49

tazi123

Original post by britchick

This is a very good answer

Edit: isn't there NO diffraction of light from the tiger around the hill, hence why you can't see it, rather than "very little diffraction"?

yh no diffraction, my bad

Reply 50

britchick

Original post by tazi123

yh no diffraction, my bad

I still didn't write as good as answer as you though! Really well-thought out

Reply 51

tazi123

Original post by britchick

I still didn't write as good as answer as you though! Really well-thought out

thanks

Reply 52

Freddy12345

For the experiment question about the standing wave I wrote. The weight straitens the wire. So the wire is fixed at both ends. The vibrator will make the wire move in a wave like motion. Since the wire is fixed, and is not moving anywhere, it remains stationary, hence a standing wave.

(edited 12 years ago)

Reply 53

yazdan

hey guys what did you write for the last question about what u can observe as the frequency changes :s

Reply 54

britchick

Original post by yazdan

hey guys what did you write for the last question about what u can observe as the frequency changes :s

I said as frequency increases, wavelength must decrease in order to keep v constant, so you will observe more nodes and antinodes along the wave.

Reply 55

britchick

Original post by Freddy12345

I said a standing wave is produced when a wave hits a boundary and is reflected in the opposite direction with an equal frequency and wavelength to the incident wave, at 180 degrees to the incident wave. Hence a standing/stationary wave because energy is stored within the wave as opposed to energy being transferred.

Reply 56

britchick

Is anyone else doing Unit 4 on Tuesday? What are your thoughts?

Reply 57

yazdan

Any chance of model answers being put up by anyone? :smile:

Reply 58

cjcmoney

I got 15m^2 . I think its right because it said the output power was 500W and it was 15% efficient so that means 3333W was input to achieve 500W output.

Reply 59

farhanyen

For the 2 mark curtain question, my answer was
-light totally internally reflects in the core of the optic fibre
-curtain is made of optic fibre
-light does not escape the optic fibre and is only released at the bottom of the curtain where optic fibre ends
-hence only the bottom of the curtain is bright

For the surface area of the solar panel question,
-power input=power output/efficency=500/15%=3333W
-A=P/F=3333/210=16m^2 (calculator value is 15.87)
How did you get15m^2.