For light of wavelength 400 nm , the index of refraction of fused quartz is 1.472 , and for light of wavelength 760 nm , it is 1.452 . Determine the speeds of light for these wavelengths in fused quartz.

Step-by-step solution

The speed of light in a medium is given by v = c n , where c = 3 10^8 m s ⁻¹ is the speed of light in vacuum and n is the refractive index of the medium. For light of wavelength 400 nm , the refractive index is n₁ = 1.472 . v₁ = 3 10^8 1.472 2.04 10^8 m s ⁻¹ For light of wavelength 760 nm , the refractive index is n₂ = 1.452 . v₂ = 3 10^8 1.452 2.07 10^8 m s ⁻¹