C11.7 Polarisation of EM Waves

What is the direction of polarisation in electromagnetic waves?

The direction of polarisation is parallel to the electric field of the wave.

What type of waves can be plane polarised?

Transverse waves can be plane polarised, oscillating in only one plane.

What are polarising filters made of?

Polarising filters are plastic films containing very long thin crystals that limit transmission of polarised light in one direction only.

What happens when two polarising filters are placed at 90 degrees to each other?

When two polarising filters are at 90 degrees, no light is transmitted.

What is unpolarised light?

Unpolarised light consists of many oscillations in different directions.

How can microwaves be polarised?

Unpolarised microwaves can be polarised using a metal grille, as found in the door of a microwave.

What is the effect of angle of incidence on reflected light?

When angle of incidence reaches a specific angle, the reflected light becomes completely horizontally polarised.

What are the specific angles for complete horizontal polarisation for air-water and air-glass?

For air-water, the angle is 53 degrees; for air-glass, it is 57 degrees.

How do sunglasses reduce glare?

Sunglasses remove glare by blocking horizontally polarised light that is reflected from surfaces like roads.

Why do TV aerials need to be oriented in a certain way?

TV aerials pick up EM waves polarised in one plane, so orientation affects reception and reduces interference.