Question

A rectangular block of glass `ABCD` has a refractive index `1.6`. A pin is placed midway on the face`AB`, Fig. When observed from the face `AD`, the pin shall.
.
A. appear to be near A
B. appear to be near D
C. appear to be near at the centre of AD
D. not be seen at all

Answer 1

For `mu=1.6` the critical angle `mu=1//sin C,` we have C= `38.7^(@)` , when from AD, as long as angle of inidence on AD of the ray emanating from pin is greater than the critical angle, the light suffers from total internal reflection and cannot be seen through AD.