Chapter 1, 2 Flashcards
Two principal quantities in circuits?
Current
Voltage
Objective of circuit analysis?
Determine unknown currents and voltages
Source
Provides energy
Load
Consumes energy for some purpose
Ideal wire
Conducts electric charge without any loss of potential
Good approximation: for many applications
Poor approximation: long-distance transmission lines, microscopic ICs
Every point on a node has same electric potential.
True or False
TRUE
Branch
Single electrical pathway
Consists of wires and elements
Elements of a branch said to be in series
Loop
Any closed pathway, both physical and conceptual
Mesh
Closed electrical pathway not containing other closed physical pathways
Branch (describe the structure)
Any circuit with two terminals
Node
Junction of two or more branches
Electric current
Rate at which charge passes through a predetermined area
Unit is ampere (A)
What does the arrow symbol indicate?
The assumed direction of the current
Current represented by i (italicized)
What electrical path is required for nonzero current?
Closed electrical path
What is the fundamental electric quantity?
Charge
What is the charge of an electron?
q(e) = -1.602 x 10^-19 Coulomb
Unit: C
What is an electric current?
Time rate or change of charge
Electric current
i (italicized)
formula?
dq/dt
AKA
C/S
1 Ampere (A) = ?
1 (C/S)
The charge (Q or q) transported by a constant current of one ampere in one second.
Provide the formula
1C = 1A (italicized) times 1s
What must be the net sum of currents crossing any closed boundary (node or supernode)?
Also provide the equation
It must equal zero.
Sum of C(n) = 0
C - L(sub1) - L(sub2) - L(sub3) = 0
C = L(sub1) + L(sub2) + L(sub3)
Kirchoff’s Current Law (KCL)
Sum of the currents at a node must equal zero.
Aka inputs = outputs
Voltage:
Usage?
Units?
Also called?
Work or energy required for the charge to move between two points in a circuit.
Unit is volts (V)
Also called Potential Difference
What does the voltage direction indicate?
What is voltage direction also known as?
Direction indicated whether energy is gained or lost by the charge.
Direction is also known as polarity.
Kirchhoff’s Voltage Law
Net change in electrical potential around a CLOSED loop is ZERO
Symbol for earth ground
o
|
—-
—
-
Symbol for ground
————
———
—
Ideal voltage source
An electrical device that will generate a prescribed voltage at its terminals independent of the current
How is the current determined in an ideal voltage source?
Determined by the circuit connected to the voltage source
Ideal current sources
Generated current independent of the voltage across its terminals
How is the voltage determined in an ideal current source?
Amount of voltage determined by the circuit
Dependent (controlled) sources
Output depends on some other voltage or current within the circuit
Resistance
Name the outcome and unit.
Resistance leads to energy dissipation in the form of heat.
Can be desired or undesired.
Unit: ohms (omega)
Ohms Law
Provide the empirical relationship and application limitations.
V (italics) = i(italics) • R
Linear relationship does not apply over large ranges of voltage or current
Symbol for resistance
—^__^——/\____/\—
The spiky squiggle.
Conductance is the inverse of resistance.
true or false?
TRUE
Formula for conductance
G = 1/R
Max power dissipation
list formulas
P = VI = I^2R = V^2/R
Short circuit
Circuit element with resistance approaches 0
Open circuit
Circuit element whose resistance approaches infinity
Series resistors
Two or more circuit elements are said to be in series if the same current flows through each element
Polarized Capacitators
Capacitors whose anode is made of a particular metal on which an insulating oxide layer forms by anodization, acting as the dielectric of the electrolytic capacitor.
