operattioms fundamentals (business) Flashcards
voltage
amount of energy per charge available to
move electrons from one point to another in a circuit.
current
the rate of charge flow and is measured in
amperes.
Resistance
Resistance is the opposition to current and is measured in ohms.
Ohms Law
V = IR
Energy
ability to do work
power
rate at which energy is used (watts)
Watt’s law
P = I x V
power supply efficiency
Efficiency of a power supply is a measure of how well it Converts ac to dc. η=(POUT/PIN)×100%,
Series Circuits
only one current path hence current everywhere is the same
series circuit total resistance
total resistance of resistors in series is
the sum of the individual resistors.
Kirchhoff’s Voltage Law
The sum of all the voltage drops around a single closed path in a circuit is equal to the total source voltage in that closed path, KVL applies to all circuits, but you must apply it to
only one closed path. In a series circuit, this is (of
course) the entire circuit.
Voltage Divider rule
The voltage drop across any given resistor in a series circuit is equal to the ratio of that resistor to the total resistance, multiplied by source voltage
resistors in parallel
Resistors that are connected to the same two points are said to be in parallel
parallel circuit
parallel circuit is identified by the fact that it has
more than one current path (branch) connected to a common voltage source
parallel circuit rule for resistance
The total resistance of resistors in parallel is
the reciprocal of the sum of the reciprocals of
the individual resistors.
Kirchhhoff’s current law
The sum of the currents entering a node is equal to the sum of the currents leaving the node
parallel current sources algebraically
Current sources in parallel can be combined algebraically into a single equivalent source
Current Divider Rule
In = ITotal (RTotal / Rn)
Superposition Theorem
a way to determine
currents and voltages in a linear circuit that has
multiple sources by taking one source at a time and
algebraically summing the results
Thevenin’s Theorem
any two-terminal,
resistive circuit can be replaced with a simple
equivalent circuit when viewed from two output
terminals.
Vth
VTH is defined as
the open circuit voltage between the two
output terminals of a circuit
Rth
defined as the total resistance appearing between the two output terminals when all sources have been replaced by their internal resistances.
Norton’s Theorem
any linear circuit can be simplified to an equivalent circuit consisting of a single current source and parallel resistance that is connected to a load
Norton’s Theorem I N
he output current when the output
terminals are shorted
Norton’s Theorem
the total resistance appearing between
the two output terminals when all sources have been replaced by their internal resistances
Maximum power transfer
maximum power is transferred from a source to a load when the load resistance is equal to the internal source resistance. Theorem assumes the source voltage and resistance are fixed
Loop Current Method
In the loop current method, you can solve for the
currents in a circuit using simultaneous equations.
Loop current method
Steps:
1. Assign a current in each loop in an arbitrary
direction.
2. Show polarities according to the assigned direction
of current in each loop.
3. Apply KVL around each closed loop.
4. Solve the resulting equations for the loop currents
Node Voltage Method
In the node voltage method, you can solve for the
unknown voltages in a circuit using KCL.
Node voltage method
Steps:
1. Determine the number of nodes.
2. Select one node as a reference. Assign voltage
designations to each unknown node.
3. Assign currents into and out of each node except the
reference node.
4. Apply KCL at each node where currents are assigned.
5. Express the current equations in terms of the voltages
and solve for the unknown voltages using Ohm’s law
