Photoelectric Effect :It is the emission of photo electron from the surface of metal when a light of certain minimum frequency falls over it.
Properties of photoelectric effect :
- The energy required to just take out electron from the metal surface is called work function (Wo).
- The minimum frequency of light below which the photoelectric effect does not takes place is called THRESHOLD FREQUENCY.
- Number of photo electron depends on the brightness or intensity of light striking on the metal surface. Brighter the light greater the number of photo electron emitted.
- As soon as the beam of light strikes the metal surface, photo electrons emitted by the metal surface. It means there is no time gap between striking of light and emission of photo electron.
- The energy of beam of light striking on metal surface is divided into two parts one for the emission of electron (work function) and the remaining as the kinetic energy of the photo electron.
Energy = work function + kinetic energy
hν = hν₀ + 1/2 mv2
{ hν= energy of light source, hν₀ = work function, 1/2 mv2 = kinetic energy of photo electron}
hν = W₀ + 1/2 mv2
1/2
mv2 = (hν - hν₀)
kinetic
energy = h(ν - ν₀)
{m= mass of electron,
h=plank’s constant(6.62 X 10-34 ), ν=frequency of light, ν₀= threshold
frequency}
W₀ = hν₀ (where, ν₀ = c/λ₀)
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