Question

Light of frequency 5×10^4 is travelling in a medium of refractive index 1.5. What is the wavelength?

Answer 1

`\lambda=\frac{c}{nf}=4000m`

Explanation:

Let's start with the definition of the refractive index:

`n=\frac{c}{v}`

`v=\lambda f`

Whence:

`n=\frac{c}{\lambda f}\implies \lambda=\frac{c}{nf}`

Now we can simply use the values we're given to calculate the wavelength (assuming that the speed of light is `300` million meters per second):

`\lambda=\frac{3\cdot 10^8}{5\cdot 10^4\cdot 1.5}=4000m`