Sampling week 2,3,4, Q9

[Xinying Wang_3C]

For question 9 in the sampling homework for week 2,3,4, I got the wavelength, but I don't know how to test if the photoelectric effect is the cause of sparking or not.

Can someone explain the second part of question 9 please?

Thanks in advance!

[Isaias Gomez D3A]

Basically, if the photoelectric effect is the cause of the sparks, that means that the energy per photon would have had to exceed the threshold energy (work function). Once you figure out the first part, you should then find the energy of the microwaves using its frequency or wavelength and compare that to your answer in part one. If the energy of the microwaves does not exceed that of the threshold energy, then the photoelectric effect cannot be the explanation, which in this case, it isn't.

[Queena Chu 3E]

you would use lambda = h*c/E to solve part one and then use E = h*v to solve part 2. Then, compare the answers and if it exceeds the normal work function then it is due to the photoelectric effect, but if it is less than the normal work function, then it is not because of the photoelectric effect.