A student very cautiously traces the path of a ray through a glass slab for different values of the angle of incidence (∠i). He then measures the corresponding values of the angle of refraction (∠r) and the angle of emergence (∠e) for every value of the angle of incidence. On analyzing these measurements of angles, his conclusion would be
(a) ∠i > ∠r > ∠e
(b) ∠i = ∠e > ∠r
(c) ∠i < ∠r < ∠e
(d) ∠i = ∠e < ∠r
Answer
- For a glass slab, light enters from rarer to denser medium, hence ray is bent towards from normal
- Thus, angle of refraction will be less than angle of incidence
- Then, when it comes out, light travels from denser to rarer medium, hence ray bends away from normal
- Hence, angle of emergence is greater than angle of refraction.
- Since opposite faces of glass slab are parallel, angle of emergence will be equal to angle of incidence
So, the correct answer is (b) - ∠i = ∠e > ∠r
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