The red border of the photoelectric effect falls on a wavelength of 350 nanometers. What is the work function?

| September 28, 2021 | education

λcr = 350 nm = 350 * 10 ^ -9 m.

h = 6.6 * 10 ^ -34 J * s.

C = 3 * 10 ^ 8 m / s.

Av -?

The red border of the photoelectric effect is called λcr, such a wavelength of the irradiated light λ, at which the photon energy Ef is enough to snatch an electron from the metal surface.

The work function Av is called the energy that must be expended to pull out an electron from the metal surface.

Eph = Av is the condition for the appearance of the phenomenon of the photoelectric effect.

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 / 350 * 10 ^ -9 m = 5.6 * 10 ^ -19 J.

Av = 5.6 * 10 ^ -19 J.

Answer: for a given metal, the work function is Av = 5.6 * 10 ^ -19 J.



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