Life is Less Than Ideal: When resistors and capacitors mix

Charges in Conductors Electric fields are created when positive charges and negative charges are separated A uniform electric field existing over a region sets up a potential difference between points in that region: DV=EDx, where Dx is the distance along a field line. If I apply a potential difference across a conducting object (including semiconductors), charges experience a force, and charge carriers will flow until the potential difference is removed.

What if charge can’t flow? Consider charge separated by two metal plates A potential difference exists between the plates An electric field exists between the plates, pointing from positive plate to negative plate No current can flow

Introducing, . . . Capacitance The battery provides the work needed to move the charges and increase their potential energy

ELECTRIC POTENTIAL (POTENTIAL) When a charge, q0, moves from one point to another in an electric field, its potential energy changes.

ELECTRIC POTENTIAL Electric potential (or potential) is defined as the potential energy per unit charge.

ELECTRIC POTENTIAL For point charges, or for spherical charge distributions, it is customary to choose the zero of potential to be at infinity.

What determines capacitance? C = e0 A/d

More about capacitors

More about capacitors U = Vq 1 eV = 1.602 x 10-19 J = energy to move electron through 1 volt

Before the next class, . . . Homework 12 (Due Monday, Feb. 25) Do Activity 11 Evaluation by Midnight tonight Do the Readings for Class 12 on Magnetism Do Reading Quiz