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I just don't get why they the inductor can't be avoided. It's this same Device that causes reactive power.

Could someone explain why reactive components like the inductor and capacitor are needed in circuit? Can't they be avoided?

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    \$\begingroup\$ Typically you don't want to avoid them because they are extremely useful. \$\endgroup\$
    – John D
    Aug 30 at 0:45
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    \$\begingroup\$ Because they do things. Why do people need resistor, transistor, battery, speaker, LED? \$\endgroup\$
    – user253751
    Aug 30 at 1:00
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    \$\begingroup\$ Good luck making a DC/DC converter with no inductors or capacitors. \$\endgroup\$
    – Hearth
    Aug 30 at 2:15
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    \$\begingroup\$ L and C are so important that the universe (as we know it) wouldn't exist without them. \$\endgroup\$
    – Andy aka
    Aug 30 at 8:28
  • \$\begingroup\$ The question may sound naive, but there's some deeper insight that it could provide when taken together with good answers. If it was up to me only, I'd reopen it, but make sure that there are no duplicates - otherwise it should be merged with dupes. \$\endgroup\$ Sep 1 at 13:24

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If all circuits worked at only one frequency, then perhaps you could minimize the use of inductors and capacitors. However, that is not the case, e.g. audio applications use the frequencies from 20 to 20,000 Hz and radio applications use the frequencies from about 15 kHz to beyond 10 GHz. In order to do useful things with these frequencies, such as filtering and modulating, you need circuit components that vary with frequency. For example, you can't build a bandpass filter with only resistors. You can't filter a rectified AC signal into a clean DC signal with only resistors. Thus we use capacitors and inductors, combined with resistors, to make useful circuits.

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    \$\begingroup\$ At only one frequency: specifically 0Hz in fact! (to avoid that is, not just minimize) \$\endgroup\$ Aug 30 at 1:57
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Every conductor is an inductor, all wires have inductance. Most circuits can ignore the inductance and they don't draw the parasitic inductance and resistance into the circuit, but if you build a PCB (or anything with conductors), then you also have inductance to deal with.

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Reactive components store energy. They are frequency dependant and may be used as filters. Resistors and amplifiers alone cannot do this without L or C.

The three fundamental passive linear time invariant electrical properties are R, L, & C. All electrical components include these elements to some extent.

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If you got a constant current, you can dump it into a capacitor to charge it with minimal energy losses.

If you got a constant voltage, you can load it with a coil, and the coil will charge, with minimal energy losses.

If you connect a constant voltage source to a capacitor, 50% of the energy is wasted in the charging process. This is inherent with capacitors - no way around it.

If you connect a constant current source to an inductor, the voltage will swing wildly, breaking down insulation, radiating and conducting interference to other circuits and nearby devices, and generally making the circuit work inefficiently. If the current source has inherently limited compliance voltage range, then the current regulation will be lost - usually wasting energy as well.

Sometimes you got a constant voltage source and have to store the energy from it efficiently, and you'll use inductors. Sometimes you have a current source and you need to store energy delivered from it - you'll use capacitors.

You need both.

But even if you don't care about storing energy, often you need to shift phase of analog signals, typically to implement filters or stabilize feedback loops. That's also impossible without capacitors and inductors.

And sometimes you just want your clock to be accurate. Crystal oscillators are electromechanical devices that act like a combination of very high Q-uality capacitance and inductance. They are, in fact, orders of magnitude better at not dissipating energy than comparable discrete inductors and capacitors. They bridge the mechanical and electrical domains using a transduction process that exposes mechanical properties of a system (a quartz beam) to an electrical circuit, and vice versa. Such transducers are common. Speakers, headphones and microphones bridge the sound pressure and electrical domains, and they behave like inductors and capacitors, depending on what sort of an acoustic circuit you connect them to.

Yes, you can use a speaker connected to an acoustic resonator to synthesize a combined capacitance and inductance.

Now we're reaching the crux of the matter, I think: the concept of inductance, capacitance and resistance is not limited to electrical circuits. It is widely implemented in mechanical, hydraulic, acoustic, seismic, and other domains. So fundamental are those concepts, that our modern technological life would be impossible if we didn't employ them.

If you want to get rid of capacitors and inductors from electrical circuits, you need to get rid of musical instruments too. Their resonators, after all, are acoustic RLC circuits. Yes, really.

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Resistance, capacitance and inductance were all discovered and are part of every electrical system. Resistors, capacitors, and inductors were invented to perform a variety of tasks. You need to expand your worls of electronics. It ia a lot of fun.

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