Light travels at 3.0 × 108 m/s in a vacuum and slows to 2.0 × 108 m/s in glass. what is the index of refraction of glass?

The index of refraction,n= 1.5

Explanation:

Index of refraction, n is given by:

n = c/ v

Given: c = speed of light= 3.0×10^8m/s

v= speed of light in glass= 2.0×10^8m/s

n= (3.0×10^8)/(2.0×10^8)

n= 1.5

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m