Studied by 9 peopleAtom is made of
nucleus and electrons
Nucleus contains
protons and neutrons
Protons are
positively charged
Electrons are
negatively charged
An electron carries what charge
-1.602x10^(-19)
What can we change about an atom?
only the number of electrons
Law of Conservation of Electric Charge
Charge cannot be created or destroyed, it can only transfer
What has to be true about an atom for it to be negatively charged?
it has to have more electrons than protons
Electric Current
movement of electric charge in a wire over a period of time
Variable for current
i
Current is measured in
amps = Columb's/second
Current flows from what to what?
Higher potential to lower potential
Electron drift goes from what to what?
lower potential to higher potential
Voltage
energy required per unit charge required to move that charge between 2 points
Voltage is measured in what?
Volts = Joule/Columb
Passive Element
electrical component that does not generate power, but dissipates, stores, and/or releases it
Ideal Wire
Conducts charge without loss of potential
Objective of Circuit Analysis
Determine unknown currents and voltages
Branch
single electrical pathway, once you have options, branch is over
Node
Junction of 2 or more branches, charge can flow without crossing a component
Node voltage is always relative to what
the reference node chosen
Components in Series
MUST be on the same branch, share the same current
Components in Parallel
Sharing same nodes on both sides, have the same voltage
To find elements in Parallel
Color each node differently Any 2 elements that have the same 2 colors on each side are in Parallel, they can be chained
Loop
Any closed pathway, required for current to flow
Mesh
A loop that does not contain other loops
Smallest quantity of charge
electron or proton
Unit for charge
Coulomb
Variable for charge
q
Electron Drift
The process of sequential migration of electrons from one atom to the next.
Ohm's law
Current (i) entering + teminal of voltage v across a resistor is given by
i=v/R
Ideal, independent voltage source
provides specified voltage across terminals regardless of load or circuit
Ideal, independent current source
provides specified current flowing through it, regardless of voltage connected to it
Passive sign convention
Direction of current is into +v terminal of device (Current must flow from higher to lower potential)
Resistive Circuit
containing only sources and resistors
Conductivity
measure of how easily electrons drift through material when external voltage is applied across it
Resistivity
inverse of conductivity
Ohm's Law
V=iR
(voltage = current * resistance) ONLY true across a resistor
Ideal Linear Resistor:
One whose resistance is constant and independent of current
Circuit topology
study of geometrical properties of electrical circuits
Kirchoff's Current Law
Algebraic sum of currents entering a node must be zero
Kirchoff's Voltage Law
Algebraic sum of voltages around a closed loop must be zero
Power
Amount of work per unit of time
Power = voltage * current
P=vi
What is the voltage at the ground
0 volts
If power across a component is positive,
then power is dissipated or consumed
If power across a component is negative,
then power is generated or supplied
What do we know about power across a resistor?
it is always positive
Law of conservation of power
the sum of the power in a system is zero
When is Ohm's law true?
ONLY across a resistor
Power across a resistor =
P=v^2/R
Voltage Division
Only applies on resistors in series User KVL at mesh
