Will the number of photoelectrons ejected be same if intensity remains same but frequency is different?

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Assuming incident frequency is above threshold frequency

In: Physics

3 Answers

Anonymous 0 Comments

One way to measure intensity is by the energy being given off by the light, and since different frequencies have different energies/photon, then the number of photons given off would have to change with frequency to maintain the same intensity. Thinkink of it this way may be useful for example if you have a solar panel and want to know how much energy it is harvesting from the sun.

Another way to measure intensity is with the candela (and I admittedly know very little about this), which is a more complicated unit that is better suited to describe how bright humans perceive a light. It takes into consideration the area the light is spread out, number of photons, and the color of light. So here again, number of photons changes with frequency. Think of it like this, you can’t see radio waves, so you would say they have 0 Candela intensity, even though they are giving off a lot of photons.

A third way to talk about intensity would be in photons/time, and if you used this metric then number of photons would remain the same regardless of frequency. This method is useful for things like nuclear chemistry, knowing the rate of particle emission can help determine how fast an element will deteriorate.

TL;DR Depends on what units your using, but generally the number of photos emitted changes with frequency.

Anonymous 0 Comments

That’s kind of a tricky question because raising frequency does mean raising the energy level of each photon. If the amount of photons is constant, the overall energy and the intensity rises. If the intensity is constant, the number of photons must be smaller in order to carry the same sum of energy with them.

Anonymous 0 Comments

Only if an electron released by Compton scattering counts as a photoneutron–and they’re considered separate things generally. For the photoelectric effetr, once the threshold is reached to free an electron adding more energy to the photon just give the eletron more kinetic energy. However, once you really crank up the photon energies, Compton scattering becomes more likely. Here the photon knocks loose an electron, but has so much energy that a photon get emitted. If that second photon is above the threshold, it can cause the photoelectric effect.