The number of waves in 7.5 cm length in vacuum is the same as the number of waves in 5 cm length of a medium . What is the refractive index of the medium ?

Options

A. `1.25`
B. `1.75`
C. `1.5`
D. `1.33`

Answer

C

Explanation

No. of waves `=("Distance")/(lambda) " " :. n_1=n_2`
`:. (7.5)/(lambda_("air"))=(5)/(lambda_("medium"))" " :. (lambda_a)/(lambda_m)=(7.5)/(5)=1.5`
`:. "" mu=(lambda_a)/(lambda_m)=(7.5)/(5)=1.5`