In the figure ABC is the cross-section of a right angled prism and BCDE is the cross-section of a glass slab. The value of theta so that light incident normally on the face AB does not cross the face BC is `(Given sin^-1 3//5=37^@)`

Options

A. `thetalt37^@`
B. `thetalt53^@`
C. `thetage37^@`
D. `thetage53^@`

Answer

A

Explanation

`sin theta_C=(mu_R)/mu_D=(6//5)/(3//2)=4/5`
`r_1=0^@ rArr r_2= lt B=90^@-theta`
Now, `r_2gt theta_c`
or `sinr_2gtsin theta_C`
`:. Sin(90^@-theta)gt4/5`
or `cos thetagt4/5…(i)`
`cos 37^@=4/5`
From Eq. (i), we see that
`thetalt37^@`