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Let P and E Denote the Linear Momentum and Energy of a Photon. If the Wavelength is Decreased, - Physics

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प्रश्न

Let p and E denote the linear momentum and energy of a photon. If the wavelength is decreased,

पर्याय

  •  both p and E increase

  • p increases and E decreases

  • p decreases and E increases

  •  both p and E decrease

MCQ
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उत्तर

both p and E increase

From the de-Broglie relation, wavelength,

`λ = h/p`       ....(1)

⇒ `p = h/λ`

Here, h = Planck's constant
             p = momentum of electron
It is clear from the above equation that `p ∝ 1/λ` .

Thus, if the wavelength `(λ)` is decreased, then momentum `(p)` will be increase .

Relation between momentum and energy :

`p = sqrt(2mE)`

Here, E = energy of electron
m = mass of electron
Substituting the value of p in equation (1), we get :

`λ = h/sqrt(2mE)` 

⇒ `sqrt(E) = h/(λsqrt(2m)`

⇒ `E = h^2/(2mλ^2`

Thus, on decreasing λ , the energy will increase . 

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पाठ 20: Photoelectric Effect and Wave-Particle Duality - MCQ [पृष्ठ ३६३]

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एचसी वर्मा Concepts of Physics Vol. 2 [English] Class 11 and 12
पाठ 20 Photoelectric Effect and Wave-Particle Duality
MCQ | Q 3 | पृष्ठ ३६३

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