Question

A student traces the path of a ray of light passing through a rectangular glass slab for three different values of angle of incidence (∠i) namely 30°, 45° and 60°. He extends the direction of incident ray by a dotted line and measures the perpendicular distance 'l' between the extended incident ray and the emergent ray. He will observe that:



(1) 'l' keeps on increasing with increase in angle of incidence
(2) 'l' keeps on decreasing with increase in angle of incidence
(3) 'l' remains the same for all three angles of incidence.
(4) 'l' is the maximum for ∠i = 45° and is less than this value both for ∠i = 30° and ∠i = 60°

Answer 1

The perpendicular distance 'l' between the extended incident ray and the emergent ray is known as the lateral shift. Lateral shift is directly proportional to the sine of the angle of incidence. i.e. $l\propto \sin i$

So, lateral shift increases as the angle of incidence increases.

Hence, the correct answer is option 1.