Physics Demo Number: 186

Approximate

Run Time: 5 min

Nicol Prisms and Double Refraction

Demo Description

Two prisms from the Garland Collection can be used to show double refraction.

Scientific Principles

• Ordinary and extraordinary rays follow different paths through doubly refracting materials.

• The two rays are both Polarized.

Equipment

• Nicol Prisms

• Overhead projector

• Aluminum pinhole mask for overhead stage

Equipment Location

• Kit (186) on [C-3-3] contains the prisms and pinhole mask.

• One may also wish to get a Polaroid filter from Kit (108) on [C-4-4].

Instructions

One can lay the pinhole mask (on the right in the first photo) on the overhead projector.

This gives a single circular dot of light on the screen.

The second photo reveals a closer view of the hole in the aluminum mask sheet.

Place the Nicol prism on top of the mask hole to discover that there are now two dots of light on the screen, which are each linearly polarized.

Rotation of the Nicol mechanism over the pinhole causes one dot on the screen to revolve in circles around the other dot.

The third photo shows a view of the apparatus with the prism off the paper to the left.

One now may place the prism over the targeted equation on the sheet and retake the photo to get the result in the fourth photo.

Notice the double imaging given the equation in this photo by the prism.

Writeup created by David A. Burba

Copyright © 2013, Vanderbilt University.   All Rights Reserved.