Question

NTSE physics question The critical angle of liquid is 300 . Its refractive Index will be (a) 4 (b) 2 (c) 3 (d) 0.5 Please explain! Thanks

Answer 1

|Sin theta| = 1/Refractive index
|sin 300| = 1/R
|-0.5| = 1/R
1/R = 0.5
R = 2

Answer is B

Answer 2

REFRACTIVE INDEX IS 2 (option b)

Given:

• Critical angle of liquid is 30°.

To find:

Refractive index of liquid ?

Calculation:

When a light ray passes from the liquid to air at the critical angle of incidence, the angle of refraction is 90°.

Let refractive index be $\mu$.

Applying Snell's Law:

$\mu \sin(i) = \mu_{air} \sin(r)$

$\implies \mu \sin( {30}^{ \circ} ) =1 \times \sin( {90}^{ \circ} )$

$\implies \mu \times \dfrac{1}{2} =1$

$\implies \mu = 2$

So, refractive index is 2 (Option b)