Midterm question  [ENDORSED]

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Sue Xu 2K
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Joined: Fri Sep 29, 2017 7:06 am

Midterm question

Postby Sue Xu 2K » Wed Nov 15, 2017 9:10 pm

Why is the statement "higher frequency light always emits electrons with higher kinetic energies" incorrect?

Brigitte Phung 1F
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Re: Midterm question

Postby Brigitte Phung 1F » Wed Nov 15, 2017 9:32 pm

This statement is incorrect in its use of the word always. Higher frequency light only emits electrons with higher kinetic energies if the energy has already surpassed that of the work function; if the light's energy has not yet reached that of the work function, no electrons would be emitted.

aTirumalai-1I
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Re: Midterm question  [ENDORSED]

Postby aTirumalai-1I » Wed Nov 15, 2017 9:32 pm

That statement would only be true given that the frequency is high enough to eject the electron from the metal surface in the first place. For example, it could be possible that the increase in frequency (and thus energy) of the incident light is still less than the work function of the metal.

Leah Thomas 2E
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Re: Midterm question

Postby Leah Thomas 2E » Wed Nov 15, 2017 10:06 pm

Ok wait so the question is not assuming that the energy required to do work has already been reached?

Emily Mei 1B
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Re: Midterm question

Postby Emily Mei 1B » Wed Nov 15, 2017 10:36 pm

@Leah No, it's not. So it's asking us to consider that the work functions of metal are unique to each metal, and that increasing the frequency still may not overcome that specific metal's work function.

Helen Shi 1J
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Re: Midterm question

Postby Helen Shi 1J » Tue Dec 05, 2017 8:14 pm

Wouldn't increasing the frequency of a light even if it originally did not have the energy to emit an electron eventually lead to an electron being emitted from the metal, because if E=hv and v increases, wouldn't the energy of the photon increase until it surpasses the work function?

Patricia Macalalag 2E
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Re: Midterm question

Postby Patricia Macalalag 2E » Tue Dec 05, 2017 8:38 pm

@Helen, not necessarily because we don't know if the threshold has been surpassed


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