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Question
CBSEENPH12047756

The frequency of a light wave in a material is 2 x 1014 Hz and wavelength is 5000 Ao.  The refractive index of material will be

  • 1.40

  • 1.50 

  • 3.00

  • 1.33

Solution

C.

3.00

Velocity of light waves in material is 

ν = v λ                    ....(i)

Refractive index of material

μ = cν                      ....(ii) 

where c is speed of light in vacuum or air

 μ = cv λ                  ....(iii)

Given:-  v = 2 × 1014 Hz

λ = 5000 Ao

 λ = 5000 × 10-10 m

c = 3 × 108 m/s

Hence, from Eq. (iii), we get

μ = 3 × 1082 × 1014 × 5000 × 10-10

μ = 3.00

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