The refractive index of glass with respect to water is `9//8`. If the velocity and wavelength of light in glass are `2 times 10^8 m//s` and `4000 A` respectively, find the velocity and wavelength of light in water.

Explanation

`_w mu_g=mu_g/mu_w=v_w/v_g implies 9/8=v_w/(2 times 10^8),`
`v_w=(9 times 2 times 10^8)/8=2.25 times 10^8 m//s`
`_m mu_g= mu_g/mu_q= lamda_w/lamda_g`
`(because mu_g= lamda/lamda_g, mu_w=lamda/lamda_w)9/8= lamda_w/4000, lamda_w=(9 times 4000)/8=4500A^c`