In Lesson

Question 1

What is meant by plane polarised waves?

Answer 1

Oscillations of particles are in one direction only
Perpendicular to the direction of wave propagation

Question 2

State why EM waves can be polarised but sound waves cannot be polarised

Answer 2

Only transverse waves can be polarised. Sound waves are longitudinal and so cannot be polarised

Question 3

[Lamp] [^filter 1] [<filter 2] [Eye]
Explain why the lamp cannot be seen with the eye

Answer 3

Light passing through polarised 1 is VERTICALLY polarised (only vertical oscillations of the light exist beyond the polariser)
only component of light in the HORIZONTAL plane can pass through polariser 2, so no light reaches the eye

Question 4

Why is there a series of maxima and minima in intensity as the polaroid is rotated?

Answer 4

Maximum transmission is when the polarising sheet is parallel to the light’s plane of polarisation
No transmission is when the polarising sheet is at right angles to the light’s plane of polarisation