Edexcel Unit 2: Physics at Work ~9th June 2014

Could someone please explain this. Its June 2010 Q3

It's like vectors, you are looking for pairs that flow in opposite directions to each other but have the same line of action - don't quote me there. This can be done easily by realising the pairs in C are almost identical and they flow in opposite directions. Visually, it is quite easy. I can't really back it up in theory, sorry!


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right! thanks
And Q10? same paper

This one was tricky. It is really asking the question 'at which current do both voltages of the components add up to 9V' you will see when current is 0.3, the graphs give 3V and 6V, adding to the 9V of the battery.


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how do you do Q4 Section A on January 2013!? I can't get my head around it yet i'm comfortable doing other similar questions.

Angle of incidence: 90°-55° = 35°
Angle of refraction = 90°

Refractive index for air to glass = sin r / sin i, because you're measuring how dense the glass is and not how optically dense the air is.

sin90° / sin35° = 1.743.

Can someone explain to me the photoelectric effect in the simplest way possible

I wasn't present for any of the lessons going over this so I have no clue what it's about - and it comes up every single year, great

I especially don't understand the equations
1) E = hf = hc/wavelength

What is E? I know h is Planck's constant but what is E?

2) eV = 1/2mv2

Is this talking about the kinetic energy of an electron?

3) f = work function / h

I have no idea what this equation is about

4) hf = 1/2mv2 + work function

No clue about this one either

Could anyone explain them to me, I would be so thankful

Also, what is the photoelectric effect even talking about? I know that it was thought that light was a wave but now evidence has been found that it could be a particle called a photon but what evidence suggests it's a particle and not a wave?

Thanks so much


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Guys, does anyone know if it's possible to continue to A2 but doing an AS subject as a retake?

Someone I know did this. He did 3 A2 subjects but also was in my class for AS physics which he was retaking, and I'm pretty sure he has an uni offer for engineering. I don't know how it is with your school though.

You should still seriously revise for this exam, it never hurts to try hard

1. Energy of a photon

2. eV is electronvolts, where 1eV = 1.6x10^-19. It's just a different unit used for very small values of energy and at times more appropriate than joules.

3. Work function is the minimum amount of energy needed from a photon to release an electron from a metals surface.

4. When the photon energy is greater than the work function of a metal, electrons are emitted from the surface. This means they must have kinetic energy. Therefore "hf" is the energy of photon = "work function" minimum photon energy needed to release electrons + "1/2mv^2" kinetic energy of the emitted electron.




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No bro, I seriously gave up revising physics on that first PH01 exam, I think I got like 30 marks or something, didn't even touch PH02 & it's in 2 days. I hope I can do what your friend Did!

I'm in the exact same position as you. I literally failed unit 1, I missed out eight whole questions because I just had no idea what the answer was. I checked the unofficial mark scheme and got around 30 right, maximum. But I learnt all of unit 2 by myself in 5 days, so hoping that you know all of unit 2 you should just start on the past papers and hopefully you can do this

The only reason it took me five days is because I had to actually learn ALL the content because I'd missed so many lessons for unit 2 then we didn't even have a physics teacher etc...

I'm going to do past papers later on today and hopefully I do okay!
Just literally do tons of past papers and see how it goes

Good luck anyways - all the best


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How come on 18a you subtract the two E.M.F's to get the total instead of adding them together? http://pastpapers.edexcel.com/content/dam/pdf/A%20Level/Physics/2013/Question%20papers%20and%20mark%20schemes/6PH02_01_que_20120525.pdf

Question on photoelectric effect....

What is the difference between work function and the threshold frequency? Is it the units? I just don't seem to be able to get my head around it...

Thanks guys