Question

a. If the angle of incidence and angle of
emergence of a light ray falling on a
glass slab are i and e respectively, prove
that, i= e.
​

Answer 1

Explanation:

If the angle of incidence and angle of emergence of a light ray falling on a glass slab are i and e respectively, prove that, i = e. b. A raibow is the combined effect of the refraction, dispersion, and total internal reflection of light.

Answer 2

Answer:

Angle of Incidence means the angle by which light is hitting on the surface and get reflected to some angle.

Refer to the Attachment

Let ABCD is the glass slab

Assume that the air Index and glass index = n₁ and n₂

From the diagram ,

Consider a light ray WX makes the ∠i on the surface AB.

Reflected light XY to the Normal NN' makes the angle ∠r₁

Refracted light YZ outside the slab CD makes the angle ∠₂

Here we observe that AB and CD are parallel and XY is transversel.

Applying snell law on first surface (AB) & CD we get simultaneously

\frac{sin i}{sinr_{1}} = \frac{n_{2}}{n_{1}}

sinr

1

sini

=

n

1

n

2

-----→(a)

\frac{sin r_{2}}{sin_{e}} = \frac{n_{1}}{n_{2}}

sin

e

sinr

2

=

n

2

n

1

----→(b)

On multiplying eq. (a) & (b) , we get

\frac{sini}{sinr_{1}} * \frac{sinr_{1}}{sine}

sinr

1

sini

∗

sine

sinr

1

or \frac{sini}{sine} = 1

sine

sini

=1

Hence,

sin i = sin e

∴ \boxed{i = e}

i=e

Hence proved.