9702 · 7.5
Polarisation — FAQ
Frequently asked questions for 9702 Polarisation. Direct answers first, then deeper explanation — then practise with marking.
How do polarised sunglasses reduce glare?
Polarised sunglasses have vertically aligned transmission axes. This orientation blocks horizontally polarised light, which is a major component of glare caused by reflections off horizontal surfaces like water, snow, or roads, effectively reducing eye strain.
What is the key difference between an unpolarised wave and a plane-polarised wave?
An unpolarised wave oscillates in all possible planes perpendicular to its direction of travel simultaneously. In contrast, a plane-polarised wave has its oscillations restricted to only one specific plane, usually after passing through a polarising filter.
Can sound waves be polarised? Why or why not?
No, sound waves cannot be polarised. This is because sound waves are longitudinal waves, meaning their oscillations are inherently parallel to their direction of energy transfer. There is no 'plane' of oscillation perpendicular to their travel to restrict, unlike transverse waves.