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 ▸Explain how resonance occurs for a driven oscillating system and describe the effect of damping on the resonant frequency.
What is the difference between a longitudinal and a transverse wave?
What is the difference between accuracy and precision?
There is a point between the Moon and the Earth where the gravitational attractions are equal and opposite. How much further is this point from the Earth than the Moon