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Home » A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB. 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 at the centre of AD.(d) not be seen at all.
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB. 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 at the centre of AD.
(d) not be seen at all.
CBSE | Class 12 | NCERT Exemplar | Physics | Ray Optics and Optical Instruments
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB. 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 at the centre of AD.
(d) not be seen at all.

 

 

 

Answer:

(a) appear to be near A.

(d) not be seen at all.

The pin will appear to be near A as long as the angle of incidence on AD of the ray emerging from the pin is smaller than the crucial angle.

 

 

 

 

 

The light suffers from total internal reflection and cannot be seen through AD when the angle of incidence of the ray emerging from pins on AD is larger than the critical angle.

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