Electric Current Definition of Current Electromotive Force Ohm’s Laws Joule’s Laws Kirchhoff’s Laws Unsteady-state Processes in a Circuit with Capacitor

Definition of Current I = nSve

Electromotive Force Efficiency of a battery:

Ohm’s Laws - in integral form - in differential form

Joule’s Laws In integral form: In differential form:

Kirchhoff’s Laws (1) The algebraic sum of the currents at a junction of a circuit is zero, (2) The algebraic sum of the potential differences across the resistances is equal to the algebraic sum of the EMFs,

Kirchhoff’s Laws (cont.) The total number of equations (1) for a network is equal to a number of branch points of a network minus one. The total number of equations (2) for a network is equal to the minimum number of ruptures needed to stop the current flow round all loops of a network.

Unsteady-state Processes in a Circuit with Capacitor (1) Charging the capacitor

Unsteady-state Processes in a Circuit with Capacitor (cont.)

Unsteady-state Processes in a Circuit with Capacitor (cont.) (2) Discharging the Capacitor