Question

Lateral displacement of the emergent ray of light through a glass slab increases with

[Assume, incident and emergent angles are very small ]

• A. increase in angle of incidence
• B. Decrease in refractive index of glass slab
• C. Increase in the wavelength of light
• D. Decrease in thickness of slab.

Answer 1

The correct option is A increase in angle of incidence

Lateral displacement is given by,

$S=\frac{t}{\cos r}\sin (i-r)$

If $i$ is very small , $r$ is also small, then $\sin i\to i,\sin r\to r$ and $\cos r\to 1$.

so that,

$\frac{\sin i}{\sin r}=\mu$ , takes the form $\frac{i}{r}=\mu$

Therefore, the expression for laternal displacement takes the form

$S=(1-\frac{1}{\mu })ti$

From the above expression, we can conclude that,

1. Lateral displacement increases with increase in angle of incidence.

2. Lateral displacement increases with increase in refractive index.

3. Lateral displacement increases with increase in thickness of slab.

4. Lateral displacement increases with decrease in wavelength of light.


Hence, option (a) is the correct answer.