Question

A bubble in glass slab ( $\mu$ =1.5) when viewed from one side appears at 5cm and 2cm from other side, then thickness of slab is:
(A) 3.75 cm
(A) 3 cm
(A) 10.5 cm
(A) 2.5 cm

Answer 1

Hint : to solve this question, we have to know about refractive index. We know that, Refractive index is defined as. The ratio of the speed of light in a vacuum to its speed in a specific medium. Refractive index is also referred to as refraction index or index of refraction. The speed of light in a medium depends on the properties of the medium.

Complete Step By Step Answer:
Refractive index we know,
Refractive index = real depth/ apparent depth case
According to the question,
Now, total apparent depth is $5 + 2 = 7cm$
If we consider x as real depth then,
X is equal to the thickness of slab, then,
$x = 1.5 \times 7 = 10.5cm$
So, the right option will be option number c.

Note :
we also have to know that the refractive index is dimensionless. It is a number that indicates the number of times slower than a light wave would be in the material than it is in a vacuum. The refractive index, represented by symbol n, is the velocity of light in vacuum divided by the velocity of light in a medium. We know that, Higher the refractive index, the higher the optical density and slower is the speed of light. Optical polymers with high refractive index allow light rays to bend more within the material, which helps in lowering the profile of the lens. Also, as the refractive index increases, the thickness of the lens decreases, resulting in less weight.