omar5478
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I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.
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kritz20
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(Original post by omar5478)
I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.
Can you explain the 14th question part (b) in edexcel physics January 2013 unit 2 paper?
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omar5478
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(Original post by kritz20)
Can you explain the 14th question part (b) in edexcel physics January 2013 unit 2 paper?
I think it would be better if you study/revise this chapter to have a better understanding of it.

http://www.physicsandmathstutor.com/...excel/topic-5/

This link will send you directly to the revision section of this chapter. I recommend that you take a look at the other stuff on the site as well as it is arguably one of the best sources for Edexcel material.

If you still have questions after finishing this revision, I would be glad to oblige.
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kritz20
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(Original post by omar5478)
I think it would be better if you study/revise this chapter to have a better understanding of it.

http://www.physicsandmathstutor.com/...excel/topic-5/

This link will send you directly to the revision section of this chapter. I recommend that you take a look at the other stuff on the site as well as it is arguably one of the best sources for Edexcel material.

If you still have questions after finishing this revision, I would be glad to oblige.
I revised that section but I need a model answer for the question I asked. So can you please give me a model answer
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kritz20
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(Original post by omar5478)
I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.
Can you explain the 16th question part (c) in edexcel physics june 2012 unit 2 paper
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AyeshaSohail101
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Does anybody have AS physics implementation and assesment guide for teachers and technicians book in pdf? Thanks a lot if anybody helps!
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kritz20
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(Original post by omar5478)
I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.
Can you explain the 11th question and the 20thquestion in edexcel physics june 2014 (IAL) unit 2 paper. I do not understandthe answer given in the marking scheme. I have mock exams next week and I needhelp
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omar5478
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(Original post by kritz20)
Can you explain the 11th question and the 20thquestion in edexcel physics june 2014 (IAL) unit 2 paper. I do not understandthe answer given in the marking scheme. I have mock exams next week and I needhelp
Question 11:

Light is a transverse wave which means that the oscillations of the medium are perpendicular to the direction of wave travel. This means that there could be multiple planes of oscillation.

When light is passed through a Polaroid filter, it is polarized, which means the oscillations occur in one plane only instead of multiple planes.The allowed plane is parallel to the plane of the filter.
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Light from all lasers is polarized, so it passes through the filter with full intensity only if it is parallel to the plane of the filter. As we rotate the filter, the intensity pf the light decreases because its component which is parallel to the filter decreases. When the the planes are perpendicular to each other at 90 degrees light is completely blocked. As you rotate further, the intensity of the light increases gradually and reaches full intensity again at 180 degrees because the planes are parallel to each other.

Question 20 requires the understanding of the whole waves chapter and I can't simply explain the answer here. I would suggest that you revise it again from multiple sources (your textbook, physicsandmathstutor.com, etc.) and then pinpoint exactly what you don't understand.
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omar5478
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(Original post by kritz20)
Can you explain the 14th question part (b) in edexcel physics January 2013 unit 2 paper?
The photoelectric effect supports the particle theory of light because it shows that the energy required to release electrons from a metal is totally dependent upon the frequency of the light, and not the intensity.The energy of the photon (planck's constant * Frequency of photon) has to be above the work function (minimum energy required for an electron to be released from the surface) for an electron to be emitted.
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omar5478
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(Original post by kritz20)
Can you explain the 16th question part (c) in edexcel physics june 2012 unit 2 paper
You will have to revise the waves chapter again due to the same reasons.
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kritz20
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(Original post by omar5478)
I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.
Can you explain why the resistance of a negative temperature coefficient thermistor decreases as the potential difference is increased with relation the equation I=nAvq
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Ahmed3651998
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Yo! I'am also givin' all three units of Physics this June, so paper three isn't that hard as most of students think but yeah its true that how to inject all the knowledge required for unit 3.
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Ahmed3651998
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Those of you who have the book Edexcel AS Physics By Hodder Education (Black Cover Page) should go thru that for all practicals and for unit 2 also ofcourse.
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carlinf
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Can someone give me the black colour pages pdf of as physics book?
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kritz20
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(Original post by omar5478)
I made this thread for any questions related to Edexcel AS physics.
I will do my best to help people with their stuff as well.

Can you explain why the kinetic energy of emitted electrons vary up to a maximum value during photo electric emission
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Timlong365
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(Original post by kritz20)
Can you explain why the kinetic energy of emitted electrons vary up to a maximum value during photo electric emission
If this were a 5/6 exam question, I'd answer it like this:
Photons are discrete packets of electromagnetic energy. When radiation is incident on a metal surface, if the energy of the photon (given by E = hf) is greater than or equal to the work function of the metal, the electron absorbs its energy and gets emitted as a photoelectron. One electron absorbs the energy of one photon. Some of the energy absorbed is used to release the electron and the rest appears as kinetic energy (so E = workfunction + KEmax). It thus follows that as the enegy of the incident photons increases, the value of KEmax increases as well (so it varies with E or frequency of radiation). The value of kinetic energy is only a maximum as some energy is transfered to the metal during collisions with lattice ions while the electrons emerge from the surface.

Please correct me if anything you see is wrong/needs improving.
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Timlong365
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(Original post by kritz20)
Can you explain why the resistance of a negative temperature coefficient thermistor decreases as the potential difference is increased with relation the equation I=nAvq
The current through the thermistor increases as the potential difference across it increases by eq. V = IR, so its temperature also increases. Its temperature increasing provides enough energy for electrons in the valence band of the semiconducting material to be elevated into the conduction band, where they are delocalised to move through the solid. The number of charge carriers per unit volume (n) thus increases so, by eq. I=nAvq, the current in the thermistor increases, so it's resistence decreases (by V = IR).
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Timlong365
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(Original post by kritz20)
I revised that section but I need a model answer for the question I asked. So can you please give me a model answer

Observations of the photoelectric effect support the particle theory of light. State on such observation and explain how it supports the particle theory of light. (3)

Photoelectrons are instantaneously emitted when radiation is incident on the metal surface. This is because one photon is absorbed by one electron so, if the photon has sufficent energy, it can immediately provide enough energy to release the electron. The wave theory would allow the energy to build up (so some time would pass before the electrons have sufficient energy to be released)

There are a number of observations you could give. Another answer could've been:

Increasing the intensity of the radiation increases the rate at which photoelectrons are emitted due to intensity being proportional to the number of photons incident per second, and one photon releases one electron.
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Timlong365
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Can someone please help me with understanding this:
Why does a graph of current against resistance look like this (for a variable resistor kept at constant temperature):
Image
I know current is inversely related to resistance but why does it curve the way it does?
(Q7, multiple choice, january 2012, unit 2)
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blazingriver
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Bcus thats an inverse curve.
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