Question

This flow chart shows the amount of energy that is emitted by each type of light.

ultraviolet > blue light > yellow light > red light
(maximum energy) (minimum energy)

In an experiment, shining which type of light on a strip of metal would be least likely to produce the photoelectric effect?
ultraviolet light
dim blue light
bright red light
bright yellow light

Answer 1

Bright red light.

Reason: photoemission depends on photon energy (frequency), not brightness. Red photons have the lowest energy, so even a bright red beam is least likely to exceed the metal's work function and produce the photoelectric effect.