Question

if we go on increasing the wavelength of light on a metal surface, what changes 1. in number of electrons, 2. the kinetic energy takes place

Answer 1

kinetic energy will change and it will be lesser than its initial value.

your question is -> if we go on increasing the wavelength of light strikes on a metal surface, what changes

1. in number of electrons,
2. the kinetic energy takes place

This question is based on photoelectric principle, according to this concept when a beam of light strikes on the surface of metal, electrons ejected from its surface.

equation of photoelectric is given by, K.E = hc/λ - Φ

where h is plank's constant , λ is wavelength and Φ is work function.

here it is clear that if wavelength (i.e., λ) is increased, hc/λ value will be decreased and then the kinetic energy gained by electrons will be decreased.

so, if we go on increasing the wavelength of light strikes on a metal surface, the kinetic energy will be decreased.

Answer 2

If the wavelength is increased, photon's energy will knock out electrons which will have lesser kinetic energy, provided the wavelength is below the threshold wavelength or energy of photons more than the work function of the metal.❤️