Presentation on theme: "Maxwell’s Equations. - Gauss’s law, which is generalized form of Coulomb’s law, that relates electric fields to electric charges."— Presentation transcript:
- Gauss’s law, which is generalized form of Coulomb’s law, that relates electric fields to electric charges.
- Gauss’s law for magnetic fields, except that there are no magnetic monopoles. Magnetic field lines are always continuous.
- Faraday’s law: an electric field is produced by changing magnetic field.
- a magnetic field is produced by an electric current, or by a changing electric field.
Maxwell’s Fourth Equation: Displacement Current
Maxwell resolved the problem of no current through the capacitor by stating that the changing electric field between the plates is equivalent to electric current.
Such strange current is called displacement current. The ordinary current is then called a conduction current.
Production Of Electromagnetic Waves
-the electric and magnetic fields at any point are perpendicular to each other and to direction of motion; -fields alternate in direction from point to point; -the electric and magnetic fields are “in phase”.
EM waves are produced by accelerating electric charges.
Speed of EM Waves
Example Calculate the wavelength: (a)Of a 60-Hz EM wave; (b)Of a 93.3 MHz FM radio wave; (c)Of a beam of visible red light from a laser at frequency 4.74x10 14 Hz.
1.Which of the following a/m waves has the highest frequency: radio, microwaves, visible light, ultraviolet light, or X-rays? 2.What is the difference between X rays and gamma rays? 3.Which of the following is not an electromagnetic wave: radio, television, blue light, infrared light, or sound? 4.What does it mean when your local disc jockey says, that “you are listening to radio 1380”?
1. Two long straight wires carry identical currents in opposite directions, as shown. At the point labeled A, is the direction of the magnetic field left, right, up, down, into the page or out of the page? A. 2. A magnet produces a magnetic field that points vertically upward. Along what line does the force on a proton act if it enters this region with a horizontal velocity toward the south? 3. A copper ring is oriented perpendicular to a uniform magnetic field. The ring is quickly stretched such its radius doubles over a short time. As the ring is being stretched, is the magnitude of the net magnetic field in the center of the loop greater than, equal to, or less than the magnitude of the uniform field? Explain. 4. Can you accelerate the stationary particle with magnetic field? An electric field? Explain.