Question

Kumar is producing the photoelectric effect by using red light. He wants to increase the energy of emitted electrons. Based on the research of Albert Einstein, what is the best way for him to do this?
Increase the intensity of red light.
Decrease the intensity of red light.
Use a different colored light that has a higher frequency.
Use a different colored light that has a lower frequency.

Answer 1

Use a different colored light that has a higher frequency.

Explanation: In the photoelectric effect the maximum kinetic energy of emitted electrons is K_max = hf − φ (Einstein), so increasing photon frequency increases electron energy. Changing intensity changes the number of electrons emitted, not their individual energies.