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AQA Physics Unit 1 PHYA1 20th May 2013

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Reply 360
Avatar for Goods
Goods
16
Original post by rainerised
Does anyone know how to do q6b on jan 13?


V=(v(t)*R)/R(t)

Use potential divider theory on each separate branch


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Original post by StalkeR47
Lol nice name milkybarkid.... I am in exact same position as you. I am fantastic with quantum and particle physics not but much with electricity. I have just asked on of my friend for the notes on physics electricity. My friend sent me these note and I will like to share these with everyone! http://s1195.photobucket.com/user/porterhouse7/library/Yahho%20Q%20and%20A/AQA%20unit%201?sort=2&page=1 :tongue:


These are terrific notes for electricity!
Reply 362
Avatar for Goods
Goods
16
Original post by L'Evil Fish
Hi, I'm in year eleven, and I'll be with AQA for Physics next year.

Does anyone have any websites with which I can look at and learn content?


Look at doctor a physics on YouTube he has some nice videos. Surely you should be revising for GCSE's rather than worrying about A level physics?


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Original post by Goods
Look at doctor a physics on YouTube he has some nice videos. Surely you should be revising for GCSE's rather than worrying about A level physics?


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For the summer (while I'm fasting, or not doing anything I'll try)

GCSEs are mind numbing:frown:
What is the likely topic of the 6 mark question in the middle?
Can someone please explain to me, is the only difference between threshold frequency and work function that you times frequence by planks constant to ge the work function? Because Work function = hf, where f is the threshold frequency, so aren't they basically the same thing, dictating the energy required by a electron to be liberated with no kinetic energy?

Also, what are all of the 6 markers that we need? I've figured out:
Photoelectric effect,
Measuring Resistance
Using an oscilloscope
Measuring internal resistance
Determinging resestivity of a wire
Ploting the IV characteristics of a junction diode

Any others that may come up?
Original post by Steroidsman123
Can someone please explain to me, is the only difference between threshold frequency and work function that you times frequence by planks constant to ge the work function? Because Work function = hf, where f is the threshold frequency, so aren't they basically the same thing, dictating the energy required by a electron to be liberated with no kinetic energy?

Also, what are all of the 6 markers that we need? I've figured out:
Photoelectric effect,
Measuring Resistance
Using an oscilloscope
Measuring internal resistance
Determinging resestivity of a wire
Ploting the IV characteristics of a junction diode

Any others that may come up?


Threshold frequency is the minimum frequency for electrons to overcome work function, as hf must be greater than this work function, otherwise no electrons are emitted from the meyal surface. Work function is simply the minimum energy required to remove an electron from it metal surface, they are both very similar thing really :smile:

For the photoelectric effect, we are not meant to know the actual experiment for the photoelectric effect are we?


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Reply 367
Avatar for Bixel
Bixel
5
Original post by Steroidsman123
Can someone please explain to me, is the only difference between threshold frequency and work function that you times frequence by planks constant to ge the work function? Because Work function = hf, where f is the threshold frequency, so aren't they basically the same thing, dictating the energy required by a electron to be liberated with no kinetic energy?

Also, what are all of the 6 markers that we need? I've figured out:
Photoelectric effect,
Measuring Resistance
Using an oscilloscope
Measuring internal resistance
Determinging resestivity of a wire
Ploting the IV characteristics of a junction diode

Any others that may come up?


Equation for work function is WF = hf - Ekmax!

But yes you are right, they pretty much dictate the same thing. Since the energy of a photon is dependant on its frequency, it must therefore be at a "threshhold frequency" in order to overcome the work function of the metal surface electrons!
Reply 368
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Bixel
5
Original post by Jimmy20002012
Threshold frequency is the minimum frequency for electrons to overcome work function, as hf must be greater than this work function, otherwise no electrons are emitted from the meyal surface. Work function is simply the minimum energy required to remove an electron from it metal surface, they are both very similar thing really :smile:

For the photoelectric effect, we are not meant to know the actual experiment for the photoelectric effect are we?


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I think it's good to have a rough idea of the experiment, i.e. you shine a source of EM radiation on the surface of a metal blah blah, but I'm not sure there'll be a 6 marker on this because I don't think it's an experiment you do in class
how many sig figs do we go to when not specified
Original post by BenChard
how many sig figs do we go to when not specified


It doesn't matter unless it says "Give your answers to an appropriate number of significant figures." Just don't go crazy with them, though. :smile:
Reply 371
Avatar for Bixel
Bixel
5
Original post by BenChard
how many sig figs do we go to when not specified


As far as I know it's however many significant figures that they give you in the information, i.e. if they ask you to work out the voltage of something and they give you current as 15.3A and resistance as 3.3 Ohms, you give your answer to the lowest amount of significant figures in the information given, which is 3.3 Ohms (2sf), so you do your answer to 2 sig figs
Original post by Bixel
As far as I know it's however many significant figures that they give you in the information, i.e. if they ask you to work out the voltage of something and they give you current as 15.3A and resistance as 3.3 Ohms, you give your answer to the lowest amount of significant figures in the information given, which is 3.3 Ohms (2sf), so you do your answer to 2 sig figs


True, but you only have to do that if it explicitly says "Give your answers to an appropriate number of significant figures" (it's the only question on which you can be penalised for sig figs). But it's good practice to do what you said.
Original post by usycool1
True, but you only have to do that if it explicitly says "Give your answers to an appropriate number of significant figures" (it's the only question on which you can be penalised for sig figs). But it's good practice to do what you said.


Significant figures are more important in Unit 2 right ? :smile:
Original post by posthumus
Significant figures are more important in Unit 2 right ? :smile:


I think they're just as important in each paper. :smile:

This is what the markscheme says:

"The use of significant figures is tested once on each paper in a designated question or part-question."

:smile:
Original post by usycool1
I think they're just as important in each paper. :smile:

This is what the markscheme says:

"The use of significant figures is tested once on each paper in a designated question or part-question."

:smile:


Oh okay thanks for that ! :smile: ... my teacher used to emphasize a lot on significant figures for that unit, I guess it's not as important as he made it out to be :tongue:
Reply 376
Avatar for Bixel
Bixel
5
Original post by usycool1
True, but you only have to do that if it explicitly says "Give your answers to an appropriate number of significant figures" (it's the only question on which you can be penalised for sig figs). But it's good practice to do what you said.


Yeah, exactly :smile:
Reply 377
Avatar for NLoR
NLoR
Could someone just quickly go over line emission spectrum and line absorption?
Not very sure about how the lines are actually made?
In the specification it says that we should know how to calculate he specific charge of an ion, how do we do this, say we had lot 2 electrons from an atom forming a +2 ion?


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Reply 379
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Bixel
5
Original post by NLoR
Could someone just quickly go over line emission spectrum and line absorption?
Not very sure about how the lines are actually made?


They're made when the electron goes from it's excited state back down to a lower energy level, emitting photons in the process. These photons have a specific wavelength depending on the difference in energy levels it goes between - that specific wavelength will be a specific colour on the line spectrum. When all of these different electrons fall back down to lower energy levels, a line spectrum is produced!

Sorry that the explanation was rough but that's the general idea!

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