Photoelectric Effect AS Question Watch

HM94
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#1
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Incident UV radiation has wavelength 220nm and current is 2 micro amps.

1) Give the value of the current when the intensity of the radiation is doubled whilst keeping wavelength constant.

2) When the wavelength is increased to 350nm, the current falls to zero. Calculate the threshold frequency and the work function.

For question 1, I assumed that the current will also double since the number of electrons emitted is proportional to the intensity. Can someone confirm this? And any help on the second question would be much appreciated.
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HM94
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Report Thread starter 9 years ago
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Does anybody know how to do the two questions?
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rbnphlp
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(Original post by HM94)
Does anybody know how to do the two questions?
Im pretty sure the first one is right
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rbnphlp
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(Original post by HM94)
Incident UV radiation has wavelength 220nm and current is 2 micro amps.

1) Give the value of the current when the intensity of the radiation is doubled whilst keeping wavelength constant.

2) When the wavelength is increased to 350nm, the current falls to zero. Calculate the threshold frequency and the work function.

For question 1, I assumed that the current will also double since the number of electrons emitted is proportional to the intensity. Can someone confirm this? And any help on the second question would be much appreciated.
Im not sure what its asking for the 2nd question threshold frequency of which wavelength??
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HM94
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I think it means the second wavelength (350nm).
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rbnphlp
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(Original post by HM94)
I think it means the second wavelength (350nm).
Since the second wavelength has not enough energy to eject the electrons no current , no electrons are ejected .
use
f=c/wavelength
and use w=hf where w is the work function.
Spoiler:
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dont forget to convert the units

Edit:f=c/wavelength.I don't know what possessed me to say its 1/wavelength
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