Explaining Reactance
04/16/2009, 09/15/2020, 02/28/2021
Critical points to consider about Inductance and Capacitance
- Everything about Capacitors is totally opposite of an Inductor!
- Inductors and Capacitors Store Energy in their respective fields.
- They do not Dissipate (Transform) Energy like Resistance does, like in the form of heat, or radiation.
- In an antenna, they give it back to the XMTR,
rather than
Radiating it as Power Transmitted.
- In this case, the antenna looks like pure resistance, at resonance.
- Inductors do not like CHANGES in current. (they "React" to those changes, see also "Time Constants" below)
- Capacitors do not like CHANGES in voltage. (they "React" to those changes, see also "Time Constants" below)
- In both cases the RATE of CHANGE is critical.
- This is why the formulas for Inductive Reactance and Capacitive Reactance have Frequency as a primary component.
- Inductors oppose an increase in current by producing a
CEMF against the supplied voltage
- They also appear as an open circuit to the change, to the source. (see L&C Comparisons)
- Capacitors oppose an increase in voltage by drawing
current
from the source from the supply
- They look like a short circuit to the change , to the source. (see L&C Comparisons)
- Inductors use the applied energy to store it in an ElectroMagnetic Field, as current begins to flow (increase).
- Capacitors use the applied energy to store it in an >ElectroStatic Field as the voltage charge increases (and current decreases).
- As the "Rate of Change" increases, as in the
frequency that is applied, an inductor will oppose the
change in current more and more, therefore appearing as a
higher ohms value.
- Hence the formula: XL = 2*(pi)*freq*Henry
- As the "Rate of Change" increases, as in the
frequency that is applied, a capacitor will draw more
and more current, therefore appearing as a
lower ohms value.
- Hence the formula: XC = 1/(2*(pi)*frequency*Farads)
(with the reciprocal relationship decreasing the Ohms as frequency increases)
- Hence the formula: XC = 1/(2*(pi)*frequency*Farads)
Examples
- See "Filter_Circuit_Ilustrations" for a number of examples
- See Windherst & VanDeGraph Systems to charge a home-made capacitor