Photoelectric Effect Clarification

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FDeCastro_1B
Posts: 54
Joined: Thu Jul 25, 2019 12:16 am

Photoelectric Effect Clarification

Postby FDeCastro_1B » Fri Oct 11, 2019 12:07 pm

Can somebody please briefly explain the correlation between the wavelength and the electrons? Why can light sources with short wavelengths eject electrons while light sources with long wavelengths can't? And how do intensity and frequencies correlate as well?

Sarah Zhari 1D
Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

Re: Photoelectric Effect Clarification

Postby Sarah Zhari 1D » Fri Oct 11, 2019 12:13 pm

Light sources with short wavelengths have high frequencies, and therefore high energy. Electrons are only ejected from a metal surface if the frequency or energy of the incoming light is equal to or is higher than the threshold energy of that particular metal. The reason why increasing the intensity of short-wavelength light does not eject electrons is because in this case, light acts as particles or photons rather than waves.

Fiona Latifi 1A
Posts: 102
Joined: Sat Sep 14, 2019 12:16 am

Re: Photoelectric Effect Clarification

Postby Fiona Latifi 1A » Fri Oct 11, 2019 12:16 pm

To add on to the previous reply, increasing the intensity of light increases the number of photons, not the energy of the photons. One photon can eject one electron to do so, the photon must have either a short wavelength or high frequency so that the photons have enough energy.

ThomasNguyen_Dis1H
Posts: 102
Joined: Fri Aug 30, 2019 12:17 am

Re: Photoelectric Effect Clarification

Postby ThomasNguyen_Dis1H » Fri Oct 11, 2019 12:20 pm

Light sources with short wavelengths would have a larger frequency since there is an inverse relationship between wavelength and frequency. Using the equation E=hv, since a higher frequency correlates to a higher energy level, the light is able to overcome the threshold energy (work function) needed to eject electrons. This is because electrons can be at different energy levels (n=1,2,3...) so the metal would have different work functions. With longer wavelengths, the light would have lower frequency, therefore having lower energy. Since it doesn't have enough energy it cannot overcome the threshold energy level and cannot eject and electron no matter how intense the intensity is. Intensity simply refers to the AMOUNT of photons coming at the metal. If the photon itself does not have enough energy to overcome the threshold energy, it cannot eject the electron. Even when the photon has enough energy and a low intensity is applied, it will still be able to eject electrons since it can overcome the work function.


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