The photoelectric effect and the energy of photons

The photoelectric effect is the phenomenon where electrons are emitted from a material when light is incident upon it. This effect can be explained using the particle nature of light, where light is composed of particles called photons.

According to the photoelectric effect, electrons are only emitted from a material if the energy of the incident photons is greater than or equal to the work function of the material. The work function is the minimum energy required to remove an electron from the material.

Given information and what it implies

In this question, monochromatic light incident on a metal surface emits electrons with kinetic energies ranging from zero to 2.6 eV. This means that the energy of the incident photons is equal to or greater than 2.6 eV, as kinetic energy is given by the equation KE = E_photon - work function.

The work function of the material is not explicitly provided in the question. However, we are given that the tightly bound electron requires 4.2 eV to remove. This implies that the work function of the material is equal to 4.2 eV, as the work function is the minimum energy needed to remove an electron.

Determining the least energy of the incident photon

To determine the least energy of the incident photon, we need to consider the case where the kinetic energy of the emitted electron is zero. In this case, the energy of the incident photon is equal to the work function.

E_photon = work function = 4.2 eV

Therefore, the least energy of the incident photon is 4.2 eV.

In summary

- The photoelectric effect explains the emission of electrons from a material when light is incident upon it.
- Electrons are emitted only if the energy of the incident photons is greater than or equal to the work function of the material.
- The given information implies that the work function of the material is 4.2 eV.
- The least energy of the incident photon is equal to the work function, which is 4.2 eV.

Answer is 6.8 eV u can solve it by using formula E= W +kinetic energy