Question

What is the speed of light in a block of glass that has an index of refraction of 2.31?

Answer 1

Given,

The refractive index of the glass slab, n=2.31

The refractive index of an object is defined as the ratio of the speed of light in a vacuum to the speed of light in that object.

That is,

`n=(c)/(v)`

Where c=3×10⁸ m/s is the speed of light in the vacuum and v is the speed of light in the given block of glass.

On rearranging the above equation,

`v=(c)/(n)`

On substituting the known values,

`\begin{gathered} v=(3*10^8)/(2.31) \\ =1.3*10^8 \end{gathered}`

Thus the speed of light in the given block of glass is 1.3×10⁸ m/s