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# Incident radiation has wavelength of 300nm. What energy do the photons have? watch

1. First question says: Calculate the threshold frequency of magnesium if the work function is 3.7 eV

I know E=hf, and that E is for the work function, so then f is the threshold frequency, so it'd be f = E/h. I convert my energy to Joules, so I get = 3.7x1.6x10^-19 J. I then use f = E/h with that energy value and plancks constant to get a frequency of 8.9 x 10^14 Hz.

Then it says "the incident radiation has a wavelength of 300nm. What energy do the photons have?"

How do I do that?
2. Need to use the equation E = hv = hc/λ

(Greek letter nu, v, mostly commonly used for frequency)
3. (Original post by iElvendork)
Need to use the equation E = hv = hc/λ

(Greek letter nu, v, mostly commonly used for frequency)
Thank you. How do I do part c (question 2c)? I really don't get energy level diagrams, so I don't have a clue.
4. (Original post by vector12)
Thank you. How do I do part c (question 2c)? I really don't get energy level diagrams, so I don't have a clue.
I'm not the best at physics, what I know is based on chemistry knowledge
My understanding is that the energy of a photon is the kinetic energy
However this web page may help you;
5. You've just got to find the difference between energy levels.

That the amount of energy being carried away by the photon
6. Max kinetic energy = energy carried by photon - work function

1/2mv^2= hf - phi (cant find the greek letter lol)

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