Question

A ray of light is incident at an angle of 70 into a medium having refractive index u The reflectd and the refracted ray are found to suffer equal deviation in opposite direction. Then u equals to..... please answer my question

Answer 1

Answer: refractive index $\mu=1$

Explanation:

From the law of reflection. angle of incidence is equal to angle of reflection.

∠i=∠r

It is given that the angle of incidence, ∠i=70°

⇒∠r=70°

From Snell's, we know that the ration of sine of incidence angle to the sine of refracted angle is a constant given by ratio of refractive indices of two medias:

$\frac{sin \theta_1}{sin \theta_2}=\frac{n_2}{n_1}=\mu$

It is given that the reflected and refracted ray suffer equal deviation. This means the angle of reflected ray is equal to the angle of refracted ray = 70°.

⇒$\frac{sin 70}{sin 70}=\mu=1$

(considering first media is air, $n_1=1$)

Answer 2

sin i=70
sin r =70
according to Snell 's law of refraction
sin i/sin r =70/70=1