Resistors
are passive devices used in electronic circuits to control the flow of current. An ideal resistor has no associated
stray capacitance or inductance, and therefore performs exactly the same in a direct current (DC) circuit as it
does in an alternating current (AC) circuit at any frequency.
Realworld
resistors made of physical components exhibit more than just a pure resistance when present in an AC circuit.
A common circuit simulator model is shown to the left. It includes the actual ideal resistor with a parallel capacitive
component representing interelement (if present) mutual capacitance, and a series inductive component representing
lead and/or solder/bond pads that respond to
Related Pages on RF Cafe  Resistors & Resistance Calculations
 Resistor and Capacitor
Color Code Charts  Resistor Markings 
Mil55342 Markings 
Resistance Conversions 
Resistor Vendors 
Parallel Water Filters
Like Parallel Resistors
alternating current. SPICEtype simulators
use this or an even more sophisticated model to facilitate more accurate calculations over a wide range of frequencies.
Equations (formulas) for combining inductors in series and parallel are given below.
Total resistance of seriesconnected resistors is equal to the sum of the individual resistances. Keep
units constant.


Total resistance of parallelconnected resistors is equal to the reciprocal of the sum of the reciprocals
of the individual resistances. Keep units constant.


