The nature of electromagnetic radiation part2

Question 1

The electric component of an electromagnetic plane wave can oscillate in

Answer 1

any direction normal to the direction of wave propagation (which is parallel to the k vector)

Question 2

A represents

Answer 2

Electric field

Question 3

B represents

Answer 3

Magnetic field

Question 4

Suppose that the wave is propagating in the z direction. It follows that the

Answer 4

electric field can oscillate in any direction that lies in the x - y plane

Question 5

The actual direction of oscillation determines the

Answer 5

polarization of the wave

Question 6

The actual direction of oscillation determines the polarization of the wave. For instance,

Answer 6

a vacuum electromagnetic wave of angular frequency ω that is polarized in x direction has the associated electric field

Question 7

a vacuum electromagnetic wave of angular frequency ω that is polarized in x direction has the associated electric field.

where ω=

Answer 7

ω=kc

Question 8

where ω=kc. Likewise, a wave polarized in the y direction has the electric field

Answer 8

Question 9

A represents

Answer 9

Horizontal linear polarization

Question 10

B represent

Answer 10

Vertical linear polarization

Question 11

Vertically polarized wave

Answer 11

is one for which the electric field lies only in the x-z plane

Question 12

Horizontally polarized wave

Answer 12

is one for which the elecric field lies only in the y-z plane

Question 13

(Vertical and horizontal polarized wave )These two waves are termed __________________

Answer 13

linearly polarized

Question 14

These two waves are termed linearly polarized, since the

Answer 14

electric field vector oscillates in a straight-line

Question 15

These two waves are termed linearly polarized, since the electric field vector oscillates in a straight-line. However,

Answer 15

other types of polarization are possible

Question 16

, other types of polarization are possible. For instance, if we combine

Answer 16

two linearly polarized waves of equal amplitude, one polarized in the x direction, and one in the y direction, that oscillate π/2 radians out of phase, then we obtain a circularly polarized wave:

Question 17

a circularly polarized wave

Answer 17

Question 18

A represents

Answer 18

Left hand circular polarization

Question 19

B represents

Answer 19

Right hand circular polarization

Question 20

if the x and y components of the electric field in the previous two expressions have different ____________________ then we

Answer 20

(non-zero) amplitudes then we obtain right-hand and left-hand elliptically polarized waves, respectively.

Question 21

(non-zero) amplitudes then we obtain right-hand and left-hand elliptically polarized waves, respectively. This nomenclature arises from

Answer 21

the fact that the tip of the electric field vector traces out an ellipse in the plane normal to the direction of wave propagation.

Question 22

A represents

Answer 22

Linear

Question 23

B represents

Answer 23

Circular

Question 24

C represents

Answer 24

Elliptical

Question 25

The Stokes parameters are

Answer 25

a set of values that describe the polarization state of electromagnetic radiation.

Question 26

The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation. They were defined by George Gabriel Stokes in 1852, as a

Answer 26

mathematically convenient alternative to the more common description of incoherent or partially polarized radiation

Question 27

a mathematically convenient alternative to the more common description of incoherent or partially polarized radiation in terms of

Answer 27

its total intensity (I), (fractional) degree of polarization (p), and the shape parameters of the polarization ellipse.

Question 28

The Stokes parameters are often combined into

Answer 28

a vector, known as the Stokes vector:

Question 29

Stokes Vector consists of four parameters (called Stokes parameters):

Answer 29

intensity I,

the degree of polarization Q,

the plane of polarization U,

the ellipticity V.

Question 30

Stokes parmeters in terms of intensities

Answer 30

I = total intensity
Q= I<sub>0</sub>-I<sub>90</sub> = differences in intensities between horizontal and vertical linearly polarized components;
U = I<sub>+45</sub> –I<sub>-45</sub>= differences in intensities between linearly polarized components oriented at +45 and -45
V = I<sub>rcl</sub> –I<sub>lcr</sub>= differences in intensities between right and left circular polarized components.

Question 31

For unpolarized light:

Answer 31

Q=U=V=0

Question 32

The degree of polarization P of a light beam is defined as

Answer 32

P=(Q²+U²+V²)^1/2/I

Question 33

The degree of linear polarization LP of a light beam is defined by neglecting U and V

Answer 33

LP = -Q/I

Question 34

Measurements of polarization are actively used in remote sensing in the

Answer 34

solar and microwave regions.

Question 35

Polarization in the microwave – mainly due to

Answer 35

reflection from the surface

Question 36

Polarization in the solar

Answer 36

– reflection from the surface and scattering by molecules and particulates.

Question 37

Active remote sensing (e.g., ___________) commonly uses

Answer 37

RADAR

polarized radiation