Chapter 28 Sources of Magnetic Field

Our approach B due to a straight wire Force between two straight parallel current carrying wires The modern def. of Ampere and Coulomb Ampere’s Law –Applications and rln to Gauss’ Law Biot-Savart Law Magnetic materials Exploration of B produced by a solenoid

Magnetic Field Due to Straight Wires On what does the magnitude of the magnetic field created by a current in a straight wire depend? What exactly is the magnitude of the magnetic field around a straight wire with a current? How is the magnetic field among parallel wires with currents calculated?

Force between two current- carrying wires How can one derive the force between two parallel wires carrying currents? What is the force’s dependence on the distance between the wires? And how does this make sense? In general, when do parallel wires with currents attract or repel each other?

Definition of the Ampere and the Coulomb How are the Ampere and Coulomb defined in terms of the magnetic interaction?

Ampere’s Law In general, what two things does Ampere’s Law relate? What precisely is Ampere’s Law? In general, in what situations is Ampere’s Law most useful? How is symmetry used to define the “Amperian” path?

Ampere’s Law (cont’d) Compare Ampere’s Law and Gauss’s Law. Use Ampere’s Law to calculate the magnetic field inside a solenoid? Use Ampere’s Law to calculate the magnetic field inside a toroid?

Biot-Savart Law How does the Biot-Savart Law allow calculation of a magnetic field from current when there is insufficient symmetry to use Ampere’s Law? What is the Biot-Savart Law? Use the Biot-savart Law to calculate B along the axis of symmetry of a current loop and from a wire segment.

Magnetic Materials What is the basis of ferromagnetism? What are magnetic domains? How is un-magnetized iron attracted by magnets? How can ferromagnetism be created and destroyed? What is the Curie temperature?

Magnetic Materials (cont’d) How do paramagnetic and diamagnetic materials behave as compared to ferromagnetic materials? What is the basis of paramagnetism? What is the basis of diamagnetism? (We will skip the very interesting subject of hysteresis.)

The end