Polarising Films

Create a selection
Polarising Films
Create a selection

A simple experiment reveals why polarizing films have been included in the Materials Library. Placing one film on top of the other, it is possible to see straight through both films; but on rotating one of the films through 90 degrees, darkness suddenly descends and it is no longer possible to see anything at all. So why does simply twisting one of the films around prevent light from travelling through? This unexpected behaviour is caused by what happens to light as it passes through a polarizer.

Light is made up of waves that vibrate in many directions, but only light waves that vibrate in a single direction are allowed through a polarizer. So, when polarizers are lined up, they both allow the same light waves through, and they appear transparent. When one is rotated however, the vibrational direction of light that they allow through is not the same and light travels through the first polarizer but cannot go through the second. Polarizers’ ability to allow light to travel from a just a single direction has made it quite useful in the design of sunglasses: by wearing glasses with a single polarizing film it becomes possible to block out the “glare” of light that is reflected from the sea or a lake.

Sample ID: 182


Donated by
King's College London
Glasses | Light

Your selections

Add materials you find interesting to your own selections.

Use the plus icon button to select a material and get started.