Explaining Reactance

09/24/2020

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)

Examples

• Power supply filter system (Concerns about "Inrush Current")
• Low-Pass-Filter, High-Pass-Filter, BandPass-Filter, Notch-Filter (Band-Pass-Reject)
• Oscillator-Tuned-Circuits
• Time Constants
• More on Time Constants
• Automotive Spark coil (and capacitor)
• See Windherst & VanDeGraph Systems to charge a home-made capacitor