Difference between Intensity and Frequency (1 Viewer)

[BigBear_25]

I am confused about the concept of photonelectrons.

What is the difference between intensity and frequency in terms of light.
For example if u use a blue light that is dull (low intesity and thus low energy) and
photoelectrons are produced. But then if u use a red light that is
bright (high intensity and thus high energy because there a more photons than the blue light used before) photoelectrons are not produced.

I know that is the frequency of the incident light drops below a threshold frequency then photoelecrons are not produced.

My question is that you are putting less energy when you use a dull blue light. Then how come you can't produce photoelectrons when using a bright red light with more energy. Also is there a difference between intensity and frequency in terms of energy.

Sorry for taking long to get to the point.

 

[insert-username]

The energy of a photon is determined by its frequency, and the intensity of light is determined by the number of photons. When a photon strikes a metal and is absorbed, it will only cause electrons to be ejected if its energy is greater than the work function of the metal. Hence, if the frequency of the light is too low (e.g. your red light example), then it doesn't matter how intense the light is (i.e. how many photons), since the energy of the photon is lower than the work function. The total energy of the light may be high, but the energy of individual photons is too low to produce the photoelectric effect (since one photon can only be absorbed by one electron - the effect is not cumulative).

What the intensity does change is the number of photoelectrons emitted (assuming that the photons have energy greater than the work function). The more photons, the more electrons struck and the more that are ejected.


I_F

 

[BigBear_25]

. The total energy of the light may be high, but the energy of individual photons is too low to produce the photoelectric effect (since one photon can only be absorbed by one electron - the effect is not cumulative).

What the intensity does change is the number of photoelectrons emitted (assuming that the photons have energy greater than the work function). The more photons, the more electrons struck and the more that are ejected.


I_F

Thanks mate that makes a lot of sense now.