The photoelectric effect summary

The photoelectric effect Summary GR 10 – 12 IEB




The Photoelectric Effect

The process that occurs when lights shines on a metal and electrons are ejected.
 Significance of the photoelectric effect - it establishes the quantum theory and it
illustrates the particle nature of light.




Bodies Particles that make up the body Energy of the particle Formula
Energy called quanta
Light Photons E = hf
Work Function
Metal Electrons (Wo) Wo = hfo

Kinetic Energy
Photoelectrons Photoelectrons E k = ½ x m x v2



 Light is shined on a metal which excites the electrons which come to the surface.
 If the energy is more than the work function of the metal the electron will be
emitted from the surface of the metal and will produce kinetic energy.




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, The photoelectric effect Summary GR 10 – 12 IEB


Formulae:
1) v = λ . f
2) E= hf
hc
3) E=
λ

4) c= f λ
5) E = Wo + Ek (max)
6) hf = Wo + ½ mv2
7) Wo = hfo

Symbol Meaning Unit of measurement
v speed of ejected electron m.s-1
λ wavelength m
f frequency of light Hz
h Planck’s constant 6,63x 10-34 J.s
c speed of light 3 x 108 m.s-1
E energy of the photon J
Wo work function of a metal J
Ek (max) maximum kinetic energy of ejected electron J
fo threshold frequency Hz
m mass of electron  9,11 x 10-31 kg



Formulas:

 m = milli = 10-3
 μ= micro = 10-6
 n = nano = 10-9
 p = pico = 10-12




Other important values:


 1 electron volt (eV) = 1,6 x10 -19 J
 mass of electron = 9,11 x 10-31




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