Electricity and Magnetism Physics 208 Dr. Tatiana Erukhimova Lectures 22 - 23

Current, Ohm’s Law, Etc.

The Continuity Equation for Steady State Currents Currents and current densities are constant in time – steady state. The flux of out of any closed surface must be zero.

For steady state situation Kirchhoff’s junction rule: The algebraic sum of the currents into any junction is zero. Kirchhoff’s loop rule: The algebraic sum of the potential differences in any loop must be zero.

Resistors in series: Resistors in parallel:

Circuits with capacitors

Circuit with capacitors

Drift velocity

Joule’s Law

Why does a light bulb burn out when you switch the light on and never when you turn it off?