Question

Lateral displacement of the emergent ray of light increases with
(A) Increases in angle of incidence
(B) Decreases in refractive index of medium
(C) Increases in the wavelength of light
(D) None

Answer 1

Hint: First of all define the term “lateral displacement” and explain it. Write the formula of lateral displacement and then relate the term. In refraction, emergent ray is parallel to the incident ray but in actual it appears slightly shifted and this shift in the position of the emergent ray as compared to the incident ray is known as lateral displacement.

Complete answer:
Lateral displacement is the perpendicular distance between the incident ray and the emergent ray. The formula of lateral displacement is given by
${{S = }}\dfrac{{{t}}}{{{{cos r}}}}{{sin (i - r)}}$
Where S = lateral shift
t = thickness of the medium
i = angle of incidence
r = angle of refraction
So, the lateral displacement depends upon the angle of incidence, the angle of refraction along with the thickness of the medium.
As per the given options, lateral displacement doesn’t depend upon neither refractive index nor wavelength of medium.
Thus, lateral displacement of the emergent ray of light increases with increases in angle of incidence.

Therefore, option (A) is the correct choice.

Note: Refractive Index or index of refraction) is defined as the ratio of the speed of light in a vacuum to the speed of light in a second medium of greater density. Refractive index is represented by the term ${{n}}$. The refractive index depends upon the wavelength, this causes white light to split into constituent colours on refraction. This phenomenon is called dispersion. For visible light, the term “normal dispersion” means that the refractive index is higher for blue coloured light than for red light colour.