State what is meant by polarized light.

Unpolarized light is incident on the surface of a plastic. The angle of incidence is θ . The reflected light is viewed through an analyser whose transmission axis is vertical.

The variation with θ of the intensity I of the transmitted light is shown in the graph.

Explain why there is an angle of incidence, for which the intensity of the transmitted light is zero.

Unpolarized light from a source is split, so that there is a path difference of half a wavelength between the two beams.

A lens brings the light to focus at point P on a screen. The lens does not introduce any additional path difference.

State and explain whether any light would be observed at P, in the case in which the polarizers have their transmission axes

(i) parallel.

(ii) at right angles to each other.

light for which the electric field is oscillating in (only) one plane;

at a particular angle of incidence the reflected light is horizontally polarized;
and will be blocked by an analyser/polarizer with a vertical transmission axis;

or

at a particular angle of incidence when the reflected and refracted rays are at right angles the reflected light/rays will be horizontally polarized;
and will be blocked by an analyser/polarizer with a vertical transmission axis;

(i) mention of superposition/interference;
interference is destructive and so there will be no light at P; 
Award [0] for correct answer with no or wrong argument.

(ii) there will be light at P;
the two sources cannot interfere because their planes of polarization are at right angles; 
Award [0] for correct answer with no or wrong argument. Award [0] if answer mentions no light at P irrespective of anything else said.