Q8 of 22 Page 157

Light of wavelength enters a medium with refractive index n2 from a medium with refractive index n1. What is the wavelength of light in second medium?

Refractive index in medium 1= n1 = c/v1

Refractive index in medium 2 = n2 = c/v2


Divide n1 by n2


n1/n2 = v2/v1 …(1)


Wavelength in medium 1 = λ1


Wavelength in medium 2 = λ2


Velocity of light in medium 1 = v1


Velocity of light in medium 2 = v2


According to the formula,


v = λf where f = frequency


For medium 1: v1 = λ1f …(2)


For medium 2: v2 = λ2 f ….(3)


divide equation (2) by (3)


v1/ v2 = λ1/λ2 …(4)


From equation (1) & (4)


v1/ v2 = λ1/λ2 = n2/n1


λ2 = (n1/n2) λ1

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