Chapter 1: Radiation From Accelerating Charges

Question 1

What is a Gauge Transformation?

Answer 1

A Transformation between two frames??

Question 2

What is Gauge Invariance?

Answer 2

A gauge transformation of the potentials which results in no change in the fields

Question 3

What is a four vector?

Answer 3

A collection of 4 quantities which transforms between frames according to the Lorentz transformation.

Question 4

What is the Distant Zone?

Answer 4

When the separation between source and observer is so large it can be treated as constant. R=|x-x’|

Question 5

What is the Poynting Vector?

Answer 5

The rate of energy of radiation:
S=ExB/mu

Question 6

What does the Poynting Flux of a charge in its instantaneous rest frame show?

Answer 6

Accelerated charges radiate energy

Question 7

In what way does a charge moving at relativistic speed produce radiation?

Answer 7

Big oval thingy, angle of 1/gamma

Question 8

What is a Retarded Potential?

Answer 8

A potential which depends on the distribution of charges at some time in the past, delayed by time required for a light signal to propagate from the source to the point of interest to arrive at time t.