The wavelength of light coming from a sodium source is 589 nm. What will be its wavelength in water? Refractive index of water 1.33.`

Explanation

The wavelength in water is `lambda = lambda_(0) // mu,` where `lambda_(0)` is the wavelength in vaccum and `mu` is the refractive index of water.
Thus
`lambda = (589)/(1.33) = 443` nm,