chapter 24 electromagnetic waves. maxwell’s equation (two versions)
TRANSCRIPT
Electromagnetic Wave
EB
Light is represented by fluctuations in the magnetic and electric field called electromagnetic waves. EM wave is a consequence of the Maxwell’s Equation.
Basic Facts about EM waves in vacuum
• Always travels at exactly the speed of light c.• E and B are always perpendicular.• E×B gives the direction of the wave.• |E|=|cB|• Two independent direction of polarization (later)
Light as a wave
From this equation you can figure out the frequency from the wavelength or vice versa. You will do this many times in HW 24.
Polarizing Filters
Electrons on long polymers (long molecules) that moves only in one direction, hence absorbing energy of the E field in that direction, but let the other direction through.
Polarization by Reflection
At the Brewster angle (or polarizing angle) θp, the reflected beam becomes polarized.
Brewster’s AngleComplete polarization by reflection occurs when the reflected beam is perpendicular to the refracted beam.
Brewster’s AnglePictures taken with polarizers at different angles. The picture on the right has the reflected light removed by the polarizer to minimize reflection.