Question

We conduct an experiment by shining 500
nm light on potassium metal. This causes electrons to be emitted from the surface via the photoelectric effect. Now we change our
source light to 450 nm at the same intensity level. Which of the following is the result from
the 450 nm light source compared to the 500 nm source?

I said that more electrons would be emitted. Is that correct? Thanks.

Answer 1

If the intensity level is in Watts, there will be fewer photons per second hitting the potassium because each photon carries more energy.

You need to know how the quantum efficiency for photoemission varies with wavelength in order to answer this question.

If the quantum efficiency is constant with wavelength between 450 and 500 nm, the photoemission current will go down, but there will be more energetic electrons.

Answer 2

Out of these choices what would you say?

1. The same number of electrons would be emitted, but they would have a lower velocity
2. The same number of electrons would be emitted, but they would have a higher velocity
3. No electrons would be emitted from the surface.
4. More electrons would be emitted from the surface.
5. Fewer electrons would be emitted from the surface.

Answer 3

Nevermind I figured it out myself.