Ph272- General Physics II (Electricity and Magnetsism)

Lecture 4: Ch. 23 - Electric Field, Gauss's Law

Key Topics

Overview

• Use Gauss's Law to find the electric field of a symmetric charge distribution. (Spherical, cylindrical, planar).
• The electric field inside the "meat" of the conductor is zero wether it is charged or not.

 Use Gauss's Law to find electric field of symmetrical objects

• Spherical symmetries: Uniform solid shpere, uniform shperical shell.
• Cylindrical symmetries: Infinite long uniform line charge, infinitely long solid and hollow cylinders.
• Planar symmetry: Uniform infinite plane.

-> Do Problems 19-18,19-22

Electric field inside conductors.

• The electric field inside the "meat" of the conductor is zero wether it is charged or not.

Reason: The electrons inside a conductor can move freely. If the electric field is not zero, there will be a net force on the electrons and hence they will move. The electrons will re-distribute and alter the electric field (because the electric field depends on the charge distribution). The electrons will re-distribute until the net electric field is zero, thereby the net force on an electron is zero and it won't move anymore. The conductor reaches static equilibrium.

Examples: See lecture.

-> Do Problem 19-27

Review

• Write a brief review below:

Back to top of page

Ph272 homepage