WEEK 2B: BASIC ELECTRICAL CIRCUITS Flashcards
an interconnection of electrical devices through which
current flows
circuit
A circuit is typically composed of
- Power source (battery, wall outlet, generator)
- Conductors or wires
- load
: A combination of various elements (or groups of elements) through
which current flows (or is expected to flow).
electric network
An electric network with the presence of loops. (That is, electrons can
flow back to an initial position if allowed to move through circuit elements.)
electric circuit
The mathematical model of a physical device
used to analyze its behavior
circuit element
- In circuit analysis, these are basic
units that cannot be subdivided into other simple circuit
elements (e.g. single resistor).
simple circuit element
May be composed of or represented
by one or more simple circuit elements (e.g. DC Machine).
general circuit element
capable of delivering/supplying power to
some external element.
active element
always consumes energy
passive element
- Active circuit element
- Voltage across it is completely independent of current passing
through it. - Its current is determined by other elements in the circuit.
indeependent voltage source
- Active circuit element
- Current passing through it is completely independent of voltage
across it. - Its voltage is determined by the other elements in the circuit.
independent current source
The source quantity (voltage or current) is determined by a voltage or
current in some other location in the system under consideration.
dependent/controlled source
- Passive circuit element
- Mathematical model:
Ohm’s Law: v = R*i
where R = resistance
resistor
circuit element with resistance
approaching zero.
short circuit
may be
treated as short circuit.
conductors
Voltage across a short
circuit
zero
circuit element with resistance
approaching infinity.
open circuit
- The process of a determining the relationships of voltages, currents,
power, and other parameters/quantities in a circuit.
circuit analysis
analysis of a circuit that is governed by direct
current (DC) sources (e.g. batteries).
DC circuit analysis
basic electrical circuit laws (4)
- Ohm’s law: V=IR
- Power equations: P = V x I = I2R = V2/R
- Kirchhoff’s Current Law (KCL)
- Kirchhoff’s Voltage Law (KVL)
ohm’s law
V = IR
power equations
P = V x I = I^2R = V^2 / R
Currents entering and leaving any node (or junction) must add up to
zero
At a node, the algebraic sum of currents is equal to zero
“total current or charge entering a
junction or node is exactly equal to the charge leaving the node as it has no other
place to go except to leave, as no charge is lost within the node“.
kirchhoff’s current law (KCL)
I(exiting) + I(entering) = 0.
refers to a connection or junction of
two or more current carrying paths or elements such as cables and components
node
for current to flow either in or out of a node a [?] must exist.
closed circuit path
About any closed loop, the algebraic sum of voltages is equal to zero
“in any closed loop network, the total
voltage around the loop is equal to the sum of all the voltage drops within the same
loop”
kirchhoff’s voltage law (KVL)
- Two electric circuits are said to be equivalent with respect to a pair of
terminals if:
- the voltages across the terminals AND
- the currents through the terminals
are identical for both circuits.
the principle of equivalence
- If V1 = V2 and I1 = I2, then with respect terminals ab and xy, circuit 1 and
circuit 2 are equivalent.
Two devices are said to be in [?] if the same current flow through
both of them. Follows from KCL
series (definition: series connection)
Two devices are said to be in [?] if they are both connected to the
same pair of nodes. From KVL, the voltage across each of them will be
the same.
parallel (definition: parallel connection)
