Archive for the ‘16 Polarisation’ Category

16 Polarisation

Tuesday, August 10th, 2010

We have referred once or twice to polarisation, but have yet to examine it in detail.

The fact is that light can be polarised. The simplest way to see this is to take an old pair of polarised sunglasses and remove one or both lenses. When you place one lens on top of the other, and sight through both, what you see depends on the relative orientation of the pair. As you rotate one lens, there are two positions, 180º apart, where light fails to get through.

From this it is clear that light, at least after passing through the first lens, has an orientation and that this is at right angles to the direction that it is travelling. This allows us to identify some light as polarised, and to ascribe to it an angle of polarisation, such as ‘vertical’, ‘horizontal’, or ‘at 45 degrees’. (more…)