8/5/08 Lecture 2 Part 2 1

Maxwell’s Equations of the Electromagnetic Field Theory

t

t

EJB

BE

B

E

000

0

0

Gauss’s Law – charge makes

an electric field

The magnetic field is solenoidal (no monopole sources).

Faraday’s Law of electromagnetic induction -- E curls around a changing B.

Ampère’s Law – current makes a magnetic field

Maxwell’s “Displacement Current”

8/5/08 Lecture 2 Part 2 2

Theory of Electromagnetic Waves

8/5/08 Lecture 2 Part 2 3

Theory of Electromagnetic Waves

8/5/08 Lecture 2 Part 2 4

Theory of Electromagnetic Waves

8/5/08 Lecture 2 Part 2 5

Photon Energy FrequencyWavelength

Applications

Each part of the electromagnetic spectrum has important applications!

8/5/08 Lecture 2 Part 2 6

With our modern technologies, we use all parts of the electromagnetic spectrum.

But how do we create the different electromagnetic waves?

8/5/08 Lecture 2 Part 2 7

8/5/08 Lecture 2 Part 2 8

8/5/08 Lecture 2 Part 2 9

Radiance = Power per unit areaper unit wavelength

Photosphere

8/5/08 Lecture 2 Part 2 10

dkThc

hcdTRadiance

]1)/[exp(

12),(

5

2

Blackbody Radiation

Radiance = Power per unit areaper unit wavelength