When red light is shone on a metal, regardless of the intensity of this light, no current will flow. However if blue light is shone on this metal a current will flow. Why does this occur?
This problem can be solved by first considering the energy of a photon e = hf. A photon of red light lacks the sufficient energy to free an electron. However a photon of blue light has a higher frequency and thus has a higher energy. This allows for a photon of blue light to free an electron and thus allow for a current to flow when a large number of photons are sent towards the metal.
JP
Related Physics A Level answers
All answers ▸A 12V lamp, 36W is switched on for 1 hour. Find the energy supplied by the battery.
Why do gravitational fields around point masses obey an inverse square law?
Resolving the forces for an object suspended on two strings.
What would happen to n and Emax when a) the intensity is reduced to 1/2 I but the wavelength λ is unchanged? b) the wavelength λ is reduced but the intensity is unchanged?