Question

If the index of refraction of a lens is 1.5, how fast does light travel in the lens?

Answer 1

`v_2=2xx10^8m/s`

Explanation:

We will use a variation of Snell's Law:

`n_1*v_1=n_2*v_2`

Speed of light in air is about: `3xx10^8m/s`

Refractive index of air is almost: `1`

Refractive index of this lens: `1.5`

Speed of light in this lens is therefore:

`v_2= (n_1*v_1)/n_2`

`v_2= (1*3xx10^8m/s)/1.5`

`v_2=2xx10^8m/s`

Answer 2

`2*10^8` meters per second

Explanation:

The refractive index of a substance is related by the equation,

`n=c/v`

• `n` is the refractive index of the substance

• `c` is the speed of light in a vacuum

• `v` is the speed of light in the substance

Rearranging for `v`, we get:

`v=c/n`

Now, we just plug in our given values, and get:

`v=(3*10^8 \ "m/s")/(1.5)`

`=2*10^8 \ "m/s"`