How is photoelectron energy related to excitation wavelength?

How is photoelectron energy related to excitation wavelength?


2 Answers

Vijay Luxmi Askiitiansexpert
357 Points
13 years ago

A photoelectron is an electron that is ejected from a substance (most often an alkali metal) after it absorbs electromagnetic radiation. In this case, shining violet light on cesium causes ejection of electrons. Some of the energy of the light goes into jarring the electron free of the metal; the rest appears as kinetic energy of the electron:

= energy to pull
one electron
out of metal
+ kinetic energy
per ejected
h = h0 + h(-0)
where is the frequency of the incoming light, and 0 is the threshold frequency for the metal (cesium in your problem). You'll have to look up that threshold frequency to complete the problem.

ashish kumar
17 Points
13 years ago

Dear Ravi,

Photoelectron energy refers to the kinetic energy of the electron emitted from the metal surface on being excited by the photons of required wavelength.

According to Einstein,

                                      hc / = ø + KE

where h = planks constant

             c = speed of light

             = wavelength of the incident photon .

             ø = work function of the material.

             KE = kinetic energy of photoelectronsA

Therefore on increasing the excitation wavelength energy of the incident photon decreases and hence the photoelectron energy decreases i.e. photoelectron energy is inversely related to excitation wavelength.

Thank you.

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