Core Atomic
Structure: Nature of light
Slide 9 of 24
The photoelectric effect
The following observations could not be
accounted for:
1. no electrons were ejected unless
the frequency of light was greater than some critical value;
2. the emitted electrons had kinetic
energies that increased as the frequency of the light increased;
3.increasing
the light intensity did not change the energy
of the electrons but did increase
the number emitted per unit time.
According to the electromagnetic wave theory,
the energy of light is independent of frequency.
How does one explain the first two observations
then?
The theory predicted that the energy of the electrons would increase as
the light intensity
increased, but as indicated above,
it did not.