The silver plates are illuminated with ultraviolet radiation with a wavelength of 150 nm. The work function

The silver plates are illuminated with ultraviolet radiation with a wavelength of 150 nm. The work function of electrons from the tungsten surface is 4.7 • 10 to the -19 power of J. Find: a) the photon energy of the given radiation; b) the red border of the photoelectric effect for tungsten; c) the maximum kinetic energy of the photoelectron.

Av = 4.7 * 10 ^ -19 J.

λ = 150 nm = 150 * 10 ^ -9 m.

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

m = 9.1 * 10 ^ -31 kg.

C = 3 * 10 ^ 8 m / s.

Eph -?

λcr -?

Ek -?

The energy of the incident photons Eph goes to knocking out electrons from the surface of the metal Av and imparting kinetic energy Ek to them.

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 / 150 * 10 ^ -9 m = 13.2 * 10 ^ -19 J.

We express the work function of Av to pull out electrons from the metal surface by the formula: Av = h * C / λcr, where λcr is the red border of the photoelectric effect.

λcr = h * C / Av.

λcr = 6.6 * 10 ^ -34 J * s * 3 * 10 ^ 8 m / s / 4.7 * 10 ^ -19 J = 4.2 * 10 ^ -7 m.

Eph = Av + ​​Ek – the law of the photoelectric effect.

Ek = Eph – Av.

Ek = 13.2 * 10 ^ -19 J – 4.7 * 10 ^ -19 J = 8.5 * 10 ^ -19 J.

Answer: Eph = 13.2 * 10 ^ -19 J, λcr = 4.2 * 10 ^ -7 m, Ek = 8.5 * 10 ^ -19 J.




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