1. Maxwell Equation Equation 1: Gauss’s law for electric field Equation 2: Gauss’s law for magnetic field There is no magnetic monopole: north and south poles ALWAYS come in pairs Equation 3: Faraday’s Law of Induction We often use Use Len’z law to determine the direction (negative sign) Changing Magnetic field induces circular electric field. Equation 4: Ampere-Maxwell Law Changing electric field induces circular magnetic field.

2. Example: Maxwell Equation Indicate the equation number most relevant to each phenomenon listed in the table. 1 2 3 4 Electromagnetic Phenomenon Coulomb's law. The displacement current. Under static conditions, excess charge resides on the surface of a conductor. The magnetic field is not a conservative field. A changing magnetic field generates an electric field. A changing electric field generates a magnetic field. Electric charge is accompanied by an electric field. Electric current is accompanied by a magnetic field. There are no magnetic monopoles. Electromagnetic waves propagate at the speed of light. (Pick two!) (1)(2)(3) (4) x x x x x x x x x xx

3. Electromagnetic Wave

4. Electromagnetic Wave: Cont Long waveRadio Wave Infrared ultraviolet X rays Gamma rays 10 10 6 10 10 10 12 10 16 10 18 10 22 10 6 10 2 10 -2 10 -4 10 -7 10 -10 10 -13  Wavelength (m) Frequency 

5. Produce EM waves Radio wave LC circuits Visible lightsThermal oscillation of atoms (heat a filament) X-rayTransition of electrons from outmost shell to inner shell. Different frequency (or wavelength) means different energy.

6. Scattering of EM waves: Why is Sky Blue incident transmission Scattered earth SunAir molecules Sun