Monochromatic light to wavelength 6000Å travels through glass of refractive index `(3)/2`. The distance travelled by the wavefront 1 picosecond is

Options

A. `100 mum `
B. `200 mum `
C. `300 mum `
D. `400 mum `

Answer

D

Explanation

`V_g=( 3 xx 10^(8))/(1.5)=2 xx 10^(8) m//s `
`:.` Distance `=V_(g) xx t=2 xx 10^(8) xx 10^(-12)`
`=2 xx 10^(-4)m=200 mu m`