11. Polarization and circular polarization. Law of Malus. Polarization by reflection, Brewster’s angle. (5p.)

Question 1

Why are electromagnetic waves transverse?

Answer 1

Electromagnetic waves are transverse waves because their both electric field vector E and the magnetic field vector B are perpendicular not only to each other but also to the direction of propagation.

Question 2

A natural light beam is unpolarized: there is no preferred plane containing the E vector. The atoms in a source of such light behave independently and emit waves whose planes of polarization are randomly oriented. (tego nie trzeba pisać, to tylko jest żeby łatwiej było zrozumieć te kolejne

Answer 2

A natural light beam is unpolarized: there is no preferred plane containing the E vector. The atoms in a source of such light behave independently and emit waves whose planes of polarization are randomly oriented. (tego nie trzeba pisać, to tylko jest żeby łatwiej było zrozumieć te kolejne

Question 3

When is light linearly polarized and when is it circularly polarized???? hMMM>??

Answer 3

Light in the form of a plane wave in space is said to be linearly polarized. If light is composed of two plane waves of equal amplitude by differing in phase by 90°, then the light is said to be circularly polarized.

(przy tym rysunku ważne jest, żeby napisać że 90°, bo rzeczywiście inaczej może się zrobić z tego elipsa, a tego nie chcemy)

ZAPIERDALAJ DO WORD PO RYSUNEK DEBILU OAIFJOIJF

Question 4

Law of Malus

Answer 4

(Malus’s law) Since the intensity of the reflected light varied from a maximum to a minimum as the crystal was rotated, Malus proposed that the amplitude of the reflected beam must be 𝐴 = 𝐴0 cos 𝜃 (o tym można wspomnieć).
The intensity of the reflected polarized light can be therefore presented as the amplitude squared, so: 𝑰 𝜽 = 𝑰 𝟎 𝐜𝐨𝐬^𝟐 𝜽 . (całą resztę warto przeczytać, ale napisać wystarczy tylko to.

Question 5

Polarization by reflection/Brewster

Answer 5

There is a particular angle of incidence, called the Brewster angle, at which the reflection coefficient for the polarization component in the plane of the figure below is equal to zero.
This means that the beam reflected from the glass is linearly polarized with its plane of polarization perpendicular to the plane of incidence.

(on to ujął tylko tak, że “at Brewster’s angle the reflected and the refracted beams are at right angles”)

So, for a light beam falling at the Brewster’s angle, the component with polarization parallel to the plane of incidence is entirely reflected, whereas the perpendicular component is partially reflected and partially refracted.