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Midterm question

Posted: Wed Nov 15, 2017 9:10 pm
by Sue Xu 2K
Why is the statement "higher frequency light always emits electrons with higher kinetic energies" incorrect?

Re: Midterm question

Posted: Wed Nov 15, 2017 9:32 pm
by Brigitte Phung 1F
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.

Re: Midterm question  [ENDORSED]

Posted: Wed Nov 15, 2017 9:32 pm
by aTirumalai-1I
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.

Re: Midterm question

Posted: Wed Nov 15, 2017 10:06 pm
by Leah Thomas 2E
Ok wait so the question is not assuming that the energy required to do work has already been reached?

Re: Midterm question

Posted: Wed Nov 15, 2017 10:36 pm
by Emily Mei 1B
@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.

Re: Midterm question

Posted: Tue Dec 05, 2017 8:14 pm
by Helen Shi 1J
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?

Re: Midterm question

Posted: Tue Dec 05, 2017 8:38 pm
by Patricia Macalalag 2E
@Helen, not necessarily because we don't know if the threshold has been surpassed