Chapter 31 Maxwell’s Equations and Electromagnetic Waves

Changing E-fields go with changing B-fields What question is raised about Ampere’s Law and capacitors from a mathematical perspective? What question is raised about Ampere’s Law and capacitors from a physical intuitive perspective? What (in words) is like a current in a capacitor?

Changing E-fields go with changing B-fields (cont’d) What is the quantitative expression for this current, and why? What is the general form of Ampere’s Law? What is meant by displacement current? And how is this reflected in Ampere’s Law?

Gauss’s Law for Magnetism What is Gauss’s Law for Magnetism? How is it analogous to Gauss’s Law for electricity? What do the differences in these laws tell about electricity and magnetism?

Maxwell’s Equations What are Maxwell’s equations in their integral form? What are Maxwell’s equations in their differential form?

Electromagnetic Waves What are Maxwell’s equations that govern the propagation of electromagnetic waves? How can equivalent equations be found for the E- and B-fields separately? Why can we conclude there are EM waves?

Electromagnetic Waves (cont’d) How is the speed of these waves figured out? What does an EM wave look like?

Energy of EM waves What is the energy density of an EM wave? How are E and B related in an EM wave, and from this, how can the energy density be expressed? What is the Poynting vector mathematically? What does the Poynting vector represent?

Energy of EM waves (cont’d) How can you tell which way an EM wave is going from its “picture” at an instant in time? What is the average value of the magnitude of the Poynting vector over one cycle on an EM wave?

the end