Question

If a beam of light from a medium with a higher indexof refraction emerges into a medium with a lower index ofrefraction, what happens? (1) The emerging beam bends towardthe normal (smaller angle). (2) The emerging beam bends away from the normal (larger angle). (3) The emerging beam does notbend at all.

Short answer

The emerging beam bends away from the normal (larger angle).

Step-by-step solution

Identification of given data

A beam of light from a medium with a higher index of refraction emerges into a medium with a lower index of refraction

Significance of Snell’s law

For a given pair of media and a given light source, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. The formula for Snell's law reads as

$n_1\sin {\theta }_1=n_2\sin {\theta }_2$ …(i)

Where, ${\theta }_1$is the angle of incidence and ${\theta }_2$is the angle of refraction

$n_{1}and{n}_2$ is the refractive index of the medium

Determining the bending of beam

When a light travel from higher refractive index medium to lower refractive index medium then $n_1>n_2$

From equation (i)

$$\begin{gathered} \sin {\theta }_2=\frac{n_1}{n_2}\sin {\theta }_1 \\ \sin {\theta }_2>\sin {\theta }_1 \end{gathered}$$

So that

${\theta }_2>{\theta }_1$

From above relation it can be say that angle of emergence is more than the angle of incident. It means the emerging beam bends away from the normal (larger angle).