Author Topic: Edexcel PHYSICS Doubts  (Read 134591 times)

Offline ABF

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Re: Edexcel PHYSICS Doubts
« Reply #90 on: June 01, 2010, 10:27:54 pm »
thank you...

Offline Darth Austrakast

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Re: Edexcel PHYSICS Doubts
« Reply #91 on: June 04, 2010, 06:30:25 am »
I have a doubt from nature of light topic

In an experiment with photoelectric emitter if frequency of incident electromagnetic radiation is increased
wat will happen to the stopping potential and saturation current? can n e 1 plz explain y?
thanx !

and another question what do we have to know from absorption spectra?
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Offline Igcseboy

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Re: Edexcel PHYSICS Doubts
« Reply #92 on: June 04, 2010, 10:59:27 am »
hello

does anybody has some good notes on Waves....... i need them urgently...


some notes on electricity and nature of light will appreciated...

Offline wakemeup

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Re: Edexcel PHYSICS Doubts
« Reply #93 on: June 04, 2010, 03:32:07 pm »
I have a doubt from nature of light topic

In an experiment with photoelectric emitter if frequency of incident electromagnetic radiation is increased
wat will happen to the stopping potential and saturation current? can n e 1 plz explain y?
thanx !

and another question what do we have to know from absorption spectra?

I'm not sure what 'stopping potential' and 'saturation current' mean so I assume you want to know what will happen to the current and the potential difference. The more you increase the frequency above the threshold value, the more kinetic energy (1/2mv^2) electrons gain. So, both the current(I=nave) and potential difference(V=W/Q) will increase.

As for absorption spectra, we're basically supposed to know that different objects absorb light differently. They all absorb specific frequencies of light. That's why you see dark parts on the absorption spectra. These are the frequencies of light that have been absorbed by the object in question. This and the photoelectric effect both provide evidence for the particle nature of light.

Hope I helped.

Offline wakemeup

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Re: Edexcel PHYSICS Doubts
« Reply #94 on: June 04, 2010, 04:16:34 pm »
hello

does anybody has some good notes on Waves....... i need them urgently...


some notes on electricity and nature of light will appreciated...


You might find this useful. Some stuff is not in the course but it's good revision nevertheless
http://www.slideshare.net/pburgess/edexcel-as-physics-waves-presentation

Offline Darth Austrakast

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Re: Edexcel PHYSICS Doubts
« Reply #95 on: June 04, 2010, 06:19:18 pm »
I'm not sure what 'stopping potential' and 'saturation current' mean so I assume you want to know what will happen to the current and the potential difference. The more you increase the frequency above the threshold value, the more kinetic energy (1/2mv^2) electrons gain. So, both the current(I=nave) and potential difference(V=W/Q) will increase.

As for absorption spectra, we're basically supposed to know that different objects absorb light differently. They all absorb specific frequencies of light. That's why you see dark parts on the absorption spectra. These are the frequencies of light that have been absorbed by the object in question. This and the photoelectric effect both provide evidence for the particle nature of light.

Hope I helped.


hey thanx that helped a lot !
yeah stopping potential is voltage and saturation current is the maximum current after which the photocurrent does not increase
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Offline Sweet_03

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Re: Edexcel PHYSICS Doubts
« Reply #96 on: June 05, 2010, 03:29:52 pm »
can anyone plz explain how to do Question 21 (c)(ii)
from June 2009 !

Offline Saladin

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Re: Edexcel PHYSICS Doubts
« Reply #97 on: June 05, 2010, 03:51:09 pm »
can anyone plz explain how to do Question 21 (c)(ii)
from June 2009 !

On it now.

Offline Saladin

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Re: Edexcel PHYSICS Doubts
« Reply #98 on: June 05, 2010, 04:02:43 pm »
Just use V=lA

Then use V=IR as the current stays the same!

Offline Ibiza279

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Re: Edexcel PHYSICS Doubts
« Reply #99 on: June 05, 2010, 04:03:05 pm »
i need notes for nature of light, mainly the particle theory and the wave theory cause i don't get it :(
live life like you'll never die but don't die like you never lived but then again its a saying n i don't believe in saying much so jus forget it . . .


Offline abuelzouz

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Re: Edexcel PHYSICS Doubts
« Reply #101 on: June 05, 2010, 04:06:41 pm »
Just use V=lA

Then use V=IR as the current stays the same!

whts V=IA ??

Offline Ibiza279

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live life like you'll never die but don't die like you never lived but then again its a saying n i don't believe in saying much so jus forget it . . .

Offline Saladin

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Re: Edexcel PHYSICS Doubts
« Reply #103 on: June 05, 2010, 04:12:35 pm »
whts V=IA ??

its the constant in the question, V= length x current.

Offline Ibiza279

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Re: Edexcel PHYSICS Doubts
« Reply #104 on: June 05, 2010, 05:21:07 pm »
those were real nice websites but i need summarised notes on the particle wave theory cause i didnt get the question in the jan 2010 paper U2 physics  based of the particle wave theory :(
live life like you'll never die but don't die like you never lived but then again its a saying n i don't believe in saying much so jus forget it . . .