Photons with an energy of 6 eV knock out electrons from the metal surface. The work function

| April 3, 2021 | education

Photons with an energy of 6 eV knock out electrons from the metal surface. The work function of an electron from a metal is 5.3 eV. What momentum do electrons acquire when they leave the metal? 1 eV = 1.6 ∙ 10-19 J. The mass of an electron is 9.1 ∙ 10-31 kg.

Eph = 6 eV = 9.6 * 10 ^ -19 J.
Avout = 5.3 eV = 8.48 * 10 ^ -19 J.
m = 9.1 * 10 ^ -31 kg.
1 eV = 1.6 * 10 ^ -19 J.
R – ?
The energy of the photon is used to pull electrons from the surface of the metal and to impart kinetic energy to them: Eph = Avykh + Ek.
Ek = Eph – Avykh.
The kinetic energy of an electron Ek is determined by the formula: Ek = m * V ^ 2/2, where m is the mass of the electron, V is the speed of the electron.
The momentum of the electron is p = m * V, p ^ 2 = m ^ 2 * V ^ 2 = 2 * m * m * V ^ 2/2 = 2 * m * Ek.
p = √ (2 * m * Ek).
p = √ (2 * m * (Eph – Avykh).
p = √ (2 * 9.1 * 10 ^ -31 kg * (9.6 * 10 ^ -19 J – 8.48 * 10 ^ -19 J) = 4.47 * 10 ^ -25 kg * m / with.
Answer: the momentum of the electron at the exit p = 4.47 * 10 ^ -25 kg * m / s.



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