Photoelectric experiment vs atomic spectra

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Photoelectric experiment vs atomic spectra

Postby Jerry_T » Sun Oct 18, 2020 9:23 pm

I know Lavelle covered this in the lecture, but what is the difference between the photoelectric experiment and atomic spectra?

Samantha Pedersen 2K
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Re: Photoelectric experiment vs atomic spectra

Postby Samantha Pedersen 2K » Sun Oct 18, 2020 10:49 pm

One key difference is that the photoelectric effect causes electrons to be completely ejected from the atom they were part of (so that they are no longer interacting with the nucleus), while atomic spectra deals with electrons making transitions between energy levels while still interacting with the nucleus/remaining within the atom they are part of.

Kushaal Madadi 2F
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Re: Photoelectric experiment vs atomic spectra

Postby Kushaal Madadi 2F » Sun Oct 18, 2020 11:43 pm

Hello! So the photoelectric experiment involves ejecting electrons from a metal surface using packets of energy (photons). Here, photons do not need a specific frequency. Instead, they simply need to exceed the frequency required to make their energy greater than that necessary to displace an electron of a given atom. Frequency determines energy because of Planck's equation: E=hv (where E is energy in joules, h is Planck's constant, and v is frequency in hertz). On other other hand, atomic spectra is a more complicated phenomenon which involves shooting electrons into gases. Within a given gas, there are many atoms. When a lot of light (from various parts of the EM spectrum) is shined into this gas many photons will encounter many electrons. At the level of each individual atom, the different photons with different frequencies will try to excite electrons. However, only some will succeed. Those excited atoms will eventually be unexcited (they get bored?) and as a result they drop to lower energy levels. In the process, they emit photons. However, the number of energy levels dropped and the energy of the photons they emit is random because some electrons drop several levels at once while others may make stops. However, the bottom line is ONLY FREQUENCIES OF PHOTONS THAT WERE ABSORBED GET EMITTED THROUGHOUT THE SAMPLE. Through analyzing the frequencies of the photons emitted, you can create a type of fingerprint for this atom that helps you identify what element it is. Hope that helps? (This is what I took away from the lecture and it may not be a 100% right).

Nico Medina
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Re: Photoelectric experiment vs atomic spectra

Postby Nico Medina » Sun Oct 18, 2020 11:51 pm

The answer above was phenomenal. For me, I just try to keep it organized in my head by remembering that photoelectric involves EJECTING, and atomic spectra involves EXCITING. Then, I remember everything stated above regarding what each term means. Hope this helps you keep it organized!

Izamary Marquez 2H
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Re: Photoelectric experiment vs atomic spectra

Postby Izamary Marquez 2H » Sun Oct 18, 2020 11:57 pm

In the experiment, was there a specific reason why they used metals (mainly copper) to reflect the e-. In addition, can an experiment like this one be both classical & Quantum mechanics by changing a few variables of the experiment.

Ayesha Aslam-Mir 3C
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Re: Photoelectric experiment vs atomic spectra

Postby Ayesha Aslam-Mir 3C » Mon Oct 19, 2020 12:31 am

Wait so in my understanding I see hte photoelectric effect as causation for atomic spectra; otherwise, the effect AFFECTS the spectra, in that the light emitted from an electron dropping energy levels causes that line of light which helps place atoms (or molecules) on the spectra in their respective position.

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