Question

Light is projected onto a semi-conductive surface. However, no electrons are ejected. What will happen when the light intensity is increased?

a) More electrons are ejected.

b) No change in electron ejection.

c) Electrons move away from the surface.

d) The surface becomes opaque.

Answer 1

Increasing the intensity of light on a semi-conductive surface will not result in the ejection of electrons unless the light's frequency is above the material's threshold frequency; intensity alone is not sufficient for electron ejection.

Step-by-step explanation:

When light is projected onto a semi-conductive surface and no electrons are ejected, increasing the intensity of the light will not result in the ejection of electrons if the frequency of the light is below the threshold frequency needed to eject electrons from that particular material. The photoelectric effect shows that it is the energy of the photons (which is related to their frequency) that determines whether electrons will be ejected, not the intensity of the light. Hence, increasing the intensity only increases the number of photons, but if these photons do not have enough energy (frequency is too low), no electrons will be ejected.