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Radiation of wavelength λ is incident on a photocell. The fastest emitted photoelectron has a speed v . If the wavelength is changed to 3 λ 4 , the speed of the fastest emitted photoelectron will be

Options

  1. A= v 4 3 1 2
  2. B= v 3 4 1 2
  3. C> v 4 3 1 2
  4. D< v 4 3 1 2

Correct answer

C. &#62; v 4 3 1 2

Step-by-step solution

1 2 mv 2 = hc &#955; - &#981; ...(i) 1 2 mv ' 2 = 4 3 hc &#955; - &#981; &#160; ...(ii) From Eqn. (i) hc &#955; = 1 2 mv 2 + &#981; On putting this Eqn. (ii) 1 2 mv &#8242; 2 = 4 3 1 2 mv 2 + &#981; - &#981; v ' 2 = 4 3 v 2 + 2 &#981; 3 m &#8658; v ' &#62; 4 3 v

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