Following results are observed when sodi | Class 11 Chemistry Chapter Structure of Atom, Structure of Atom NCERT Solutions

Question:

Following results are observed when sodium metal is irradiated with different wavelengths.

Calculate (a) threshold wavelength and, (b) Planck’s constant.

               λ (nm) 500 450

400

       v × 10–5 (cm s–1) 2.55 4.35 5.35

 

Answer:

(a) Let us suppose threshold wavelength to be λD nm (= λ0 x 10-9 m), the kinetic energy of the radiation is given as:

h(v-v0)=1/2 mv2

Or

hc(1/λ - 1/λD) = 1/2 mv2

Threshold wavelength (λD)= 540 nm

 Substituting this value in equation iii,we get

= h  x (3x108)/10-9 [1/400-1/540]

= [(9.11x10-31)(5.20x106)2] / 2

=6.66x10-34Js


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Comments

  • Mayukh Majumdar
  • 2019-06-27 09:59:12

An excellent solution.


  • Mrinmay Majumdar
  • 2019-05-28 08:24:38

Thank you


  • Enough hfbghv
  • 2019-05-21 14:53:00

Hey you have copied wrong values in second case it's 4.35 not 3.45


  • Chandra Gupta
  • 2018-05-04 12:19:25

Somehow answer is git by you Nothing explained clearly 1st you should take threshold wevelength from let then put photoelectric formulae then put values avg. Of given data


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 52: Following results are observed when sodium metal is irradiated with different wavelengths. Calcul....