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 the wave - particle duality
In a particle accelerator, you accelerate an electron. Afterwards, you measure it's energy to be 350 keV. Tell my why you can't find the speed from this energy using your knowledge of classical mechanics.
Give the definition simple harmonic motion and write down the defining equation for such motion stating the meaning of any symbols involved.
Describe and explain the life cycle of a star?