You decide to perform a photoelectric effect experiment on uranium metal. The wo

Question

You decide to perform a photoelectric effect experiment on uranium metal. The work function for uranium metal is 347 kJ/mol. You have two lasers available to you.

Laser #1: A purple laser with a wavelength output of 405 nm and a power output of 50 milliWatts (50 mJ/s)

- Laser #2: An XeCl ultraviolet laser with a wavelength output of 308 nm and a power output of 25 milliWatts (25 mJ/s)

a. Calculate the energy of a single photon generated by each laser. Report your answer in Joules.

b. Calculate the number of photons per second being emitted by each laser

( answers for A . laser #1: Ephoton = 4.91 × 10^–19 J ; Laser #2: Ephoton = 6.45 × 10^–19 J )

( answers for B: Laser #1 :1.02 × 10^17 photons/s ; Laser #2: 3.88 × 10^16 photons/s )

I know the answer can you just explain how to get the answer and what equations to use? thank you!

Explanation / Answer

a) E photon= h x c/wavelength

h= 6.626x10-34 J/s

c= 3x108 m/s

Laser #1:

E= 6.626x10-34 J/s x 3x108 m/s/405x10-9m= 4.91x10-19J

Laser #2:

E=  6.626x10-34 J/s x 3x108 m/s/ 308x10-9m= 6.45x10-19J

b) Laser #1:

1 photon -------- 4.91x10-19J

x= 1.02x1017 photons/s---------- 50x10-3 J

Laser #2:

1 photon -------- 6.45x10-19J

x= 3.88x1016 photons/s---------- 25x10-3 J

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