In the photoelectric effect, what happens when light hits the metal? A. Electrons are knocked off atoms, causing electricity to flow.
B. Electricity is produced in the metal, causing light to be emitted.
C. Light is reflected off the metal, causing electrons to form.
D. Electrons are pumped into the metal, causing electricity to flow.

A. Electrons are knocked off atoms, causing electricity to flow.

Explanation:

Photoelectric effect is defined as emission or ejection of electrons from the surface of a metal when a light of certain frequency falls on the surface of the metal. Electrons emitted in this effect can be called photoelectrons.

The light which falls on the surface of the metal must be of sufficiently high frequency called as threshold frequency.

Thus light knocks off the electrons and thus the flow of electrons will result in the production of electricity.

Thus the correct option is Electrons are knocked off atoms, causing electricity to flow.