Electrical Fundamentals Definitions

Electric Charge

give: units, symbol

Physical property of matter responsible for electrical phenomena

Units: [C] coulombs

Symbol: Q, q, q(t)

4 Properties of Electric Charge

1. charge can be positive or negative

2. opposite charges attract and like charges repel

3. elementary charge e = 1.602×10^-19 C

4. charge can be neither created nor destroyed in a closed region

Electric Current

give: units, symbol

flow of electric charge with respect to time

Units: [A] amps

symbol: I, i, i(t)

“Conventional” Current

The opposite of electron flow

Voltage

give: units, symbol

“electrical pressure”, the energy required to move charge

Units: [V], volts

Symbol: V, v

Power

Give: units, symbol

the time rate of change of energy

Units: [W] watts

Symbol: P, p, p(t)

Conservation of Power

Power supplied by a circuit needs to equal the power dissipated by it

Nodes

Electrical Connections between two or more elements

Extraordinary Node

3+ elements connected

Ordinary Node

Only 2 connections

Branches

Elements between nodes

Path

Series of branches for which no node is encountered more than once

Loop

Path that starts and ends at the same node. Loops can enclose other loops

Mesh

Loop that doesn’t enclose other loops

Ground

Reference node at which we say voltage is zero

Node Voltage

The voltage difference between a node and a ground

Ohm’s Law

V=IR

Va-Vb = IR