What is Snell's law??

Question

I have to present something about snell's law but i don't exactly know what it is and what experiment i have to use.

Answer 1

Snell’s law describes the bending of light as it moves between mediums with two different indices of refraction.

The formula is,
n_1 * sin (theta_1) = n_2 * sin (theta_2)
Where n_1 and n_2 are the indices of refraction for the initial and final medium which the light will be traveling in, and theta_1 and theta_2 are in the incident angle the light hits the new surface and then refracted angle of the light as it passes through, both of which are measured with respect to the normal.

An experiment which one can do to demonstrate refraction would be to take a laser pointer and shine it into a dense, but optically transparent, medium (like water or such), and show how the light bends depending on what angle the light hits the surface.

As you might or might not be able to tell from the formula above, there is a particular, special, angle which arrives from this law which causes a phenomenon known as “total internal reflection”, where the incident light hits at just the right angle such that it is totally reflected back into the original medium and not transmitted through. It is if the second medium acts as a mirror in this case.
This angle, called the critical angle, can be found as the arcsin (n_2 / n_1) = sin^-1 (n_2 / n_1).
Total internal reflection is also a very good experiment one can do to illustrate Snell’s law.

Also, if one does not have something as useful as a laser pointer for an experiment such as this, one could also simply demonstrate refraction by placing a long straight object (like a pencil) into water and observing how the object seems to bend and/or break. The light one observes reflecting off the object in the air hits your eyes at one angle whereas the light coming from the water must first refract before hitting your eyes, causing the object to appear bent/broken in some circumstances.

Answer 2

Snells Law is about refraction of a beam of light (or other electromagnetic radiation) at the interface between two areas with different indices of refraction. If the index of refraction of the two materials is n1 and n2, and the incident angles of a beam of light are Θ1 and Θ2 with respect to a normal, then
n1sin(Θ1) = n2*sin(Θ2)

HTH ☺


Doug