Question

Four students P, Q, R and S traced the path of a ray of light passing through a glass slab for an angle of incidence 40° and measured the angle of refraction. The values as measured them were 18°; 22°; 25° and 30° respectively. The student who has performed the experiment methodically is

(A) P

(B) Q

(C) R

(D) S

Answer 1

The student R has performed the experiment methodically. The reason can be explained using Snell's law.

According to Snell's law,

`sini/sinr=mu_g`

Here,

i = Angle of incidence

r = Angle of refraction

μ_g = Refractive index for glass

The angle of refraction measured by student R is most appropriate as it verifies the Snell's law.

Given:-

i = 40^o

The angle of refraction measured by student R, r = 25^o.

Also,

sin40^o = 0.642

sin25^o = 0.422

Now,

`(sin40^@/sin25^@)=0.642/0.422=1.52`

The refractive index for glass is 1.5; it verifies the result derived above.

Hence, the correct option is C.

Disclaimer: The values of sin40^o and sin25^o can be obtained using trigonometric tables.