Review: Ohm’s Law Formulas There are three forms of Ohm’s Law: V = IR I = V/R R = V/I where: V = Voltage I = Current R = Resistance Fig. 3-4: A circle diagram to help in memorizing the Ohm’s Law formulas V = IR, I = V/R, and R= V/I. The V is always at the top. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Series and Parallel Connections Serial connection Parallel connection

Series and Parallel Series: Two or more elements are in series if they are cascaded or connected sequentially and consequently carry the same current. Parallel: Two or more elements are in parallel if they are connected to the same two nodes and consequently have the same voltage across them.

Learning objectives AC voltage source Capacitors

Direct current and alternating current A direct current (dc) remains constant (both in direction and magnitude) with time. + ve An alternating current (ac) varies sinusoid ally with time. - ve

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AC Source Symbols

Learning objectives AC voltage source Capacitors

How Charge Is Stored in the Dielectric A capacitor consists of two conductors separated by a dielectric (insulator). Capacitors store energy in the electric field. Storage means the charge remains after the voltage source is disconnected. The measure of how much charge is stored is the capacitance C. Fig. 16-1: Capacitance stores the charge in the dielectric between two conductors. (a) Structure.

The Farad Unit of Capacitance Capacitance C is a measure of capacitor in storing electric charge under voltage. The farad (F) is the basic unit of capacitance C. One farad of capacitance C equals one coulomb of charge stored in the dielectric with one volt applied. C=Q/V Most capacitors have capacitance values less than 1 F: C = 1 μF (microfarad) = 1 × 10-6 F C = 1 nF (nanofarad) = 1 × 10-9 F C = 1 pF (picofarad) = 1 × 10-12 F

Capacitor Symbol