L3

Question 1

Polarization

What can it be?

Answer 1

Polarization can be linear, circular, or elliptical.

• Linear: E_x and E_y have no phase difference.
• Elliptical: E_x and E_y have phase difference.

Question 2

Poynting vector and Theorem

Answer 2

• Describes energy flux of the electromagnetic field.
• Poynting theorem: Rate of energy transfer per unit volume equals the work done on the charge distribution plus the energy flux.

Question 3

Radiation pressure

Answer 3

• Pressure from electromagnetic radiation.
• Example: Sunlight at 1 AU exerts pressure of 9 x 10^-6 Pa.

Question 4

Intensity of optical field

Answer 4

• Given by the magnitude of the time-averaged Poynting vector.
• Intensity is averaged over the fast varying optical cycle.

Question 5

Moment of light

Answer 5

• Momentum given to an object by light.
• Depends on cross-section area A and time.