Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12
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Find the Maximum Magnitude of the Linear Momentum of a Photoelectron Emitted When a Wavelength of 400 Nm Falls on a Metal with Work Function 2.5 Ev. - Physics

Sum

Find the maximum magnitude of the linear momentum of a photoelectron emitted when a wavelength of 400 nm falls on a metal with work function 2.5 eV.

(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)

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Solution

Given :-

wavelength of light , `λ = 400  "nm" = 400 xx 10^-9  "m"`

Work function of metal, `phi = 2.5  "eV"`

From Einstein's photoelectric equation,

Kinetic energy = `(hc)/λ - phi`

Here, c = speed of light

h = Planck's constant

`therefore K.E. = (6.63 xx 10^-34 xx 3 xx 10^8)/(4 xx 10^-7 xx 1.6 xx 10^-19) - 2.5  "eV"`

`= 0.605   "eV"`

Also , `K.E. = p^2/(2m)`

where p is momentum and m is the mass of an electron.

`therefore p^2 = 2"m" xx K.E.`

`⇒ p^2 = 2 xx 9.1 xx 10^-31 xx 0.605 xx 1.6 xx 10^-19`

`⇒ p = 4.197 xx 10^-25  "kg - m/s"`

  Is there an error in this question or solution?
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APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 20 Photoelectric Effect and Wave-Particle Duality
Q 17 | Page 365
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