Will the photoelectric effect occur in zinc under the action of radiation having a wavelength of 0.45 μm?

| June 10, 2021 | education

Will the photoelectric effect occur in zinc under the action of radiation having a wavelength of 0.45 μm? The work function of electrons from zinc is 4.2 eV. Planck’s constant H = 4.136 * 10 ^ – (15) eVs.

λ = 0.45 μm = 0.45 * 10 ^ -6 m.

Av = 4.2 eV = 6.72 * 10 ^ -19 J.

h = 4.136 * 10 ^ -15 eV * s = 6.6 * 10 ^ -34 J * s.

C = 3 * 10 ^ 8 m / s

Eph -?

The energy of the incident photons Eph goes to knock out electrons from the surface of the metal Av and impart kinetic energy Ek.

Eph = Av + ​​Ek.

For the photoeffect to occur, it is necessary that the photon energy be sufficient to knock out electrons from the metal surface.

Eph ≥ Av.

The energy of photons Eph is expressed by the formula: Eph = h * C / λ, where h is Planck’s constant, C is the speed of light, λ is the wavelength of photons.

Eph = 6.6 * 10 ^ -34 J * s * 3 * 10 ^ 8 m / s / 0.45 * 10 ^ -6 m = 4.4 * 10 ^ -19 J.

We see that Eph <Av, therefore the energy of the photons is not enough for the phenomenon of the photoelectric effect.

Answer: There will be no photo effect.



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