1.

Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material of the prism is mu, a ray, incident at an angle theta, on the face AB would get transmitted through the face AC pf the prism provided.

Answer»

`THETA gt SIN^-1 [mu sin (A-sin-1((1)/(mu)))]`
`theta lt sin^-1 [mu sin (A-sin-1((1)/(mu)))]`
`theta gt cos^-1 [mu sin (A+sin-1((1)/(mu)))]`
`theta lt cos^-1 [mu sin (A+sin-1((1)/(mu)))]`

SOLUTION :
For TRANSMISSION, `r_2lt i_c` (Critical ANGLE)
`thereforeA-r_1 lt i_c``(because r_1+r_2=A)`
`thereforesin(A-r_1) lt sini_c`
`therefore sin(A-r_1) lt (1)/(mu)``(because sini_c=1/mu)`
`therefore A-r_1 lt sin^(-1)(1/mu)`
`thereforer_1 gt A-sin^(-1)(1/mu)`
`thereforesinr_1 gt sin[A-sin^(-1)(1/mu)](because sin theta=mu sin r_1)`
`therefore(sin theta)/(mu) gt sin[A-sin^(-1)((1)/(mu))]`
`therefore sin theta gt mu sin(A-sin^(-1)""(1)/(mu))`
`therefore theta gt sin^(-1)(musin(A-sin^(-1)""(1)/(mu)))`


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