Monochromatic light of a given wavelength is incident on a metal surface. however, no photoelectrons are emitted. if electrons are to be ejected from the surface, how should the incident light be adjusted?
o light of a shorter wavelength should be used.
o the intensity of the light should be increased.
o the intensity of the light should be decreased.
o light of a longer wavelength should be used.

Light of a shorter wavelength should be used.

Explanation:

This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .

The experiments that have been carried out show that increasing  or decreasing the intensity of the light will not cause the photoelectrons to be emitted, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.

And a higher frequency corresponds to a shorter wavelength according to the equation:

(where is frequency, the speed of light, and the wavelength)

So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.