Capacitive reactance

Chapter Capacitive reactance

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • 14CHAPTERCapacitive reactanceINDUCTIVE REACTANCE IS SOMETHING LIKE RESISTANCE, IN THE SENSE THAT ITis a one-dimensional, or scalar, quantity that can vary from zero upwards without limit.Inductive reactance, like resistance, can be represented by a ray, and is measured inohms.Inductive reactance has its counterpart in the form of capacitive reactance. Thistoo can be represented as a ray, starting at the same zero point as inductive reactance,but running off in the opposite direction, having negative ohmic values (Fig. 14-1).When the ray for capacitive reactance is combined with the ray for inductive reactance,a number line is the result, with ohmic values that range from the huge negative num-bers, through zero, to huge positive numbers.24714-1Inductive and capacitive reactance can be represented on a complete ohmic numberline.Capacitors and direct currentSuppose that you have two big, flat metal plates, both of which are excellent electricalconductors. Imagine that you stack them one on top of the other, with only air in between.What will take place if you connect a source of dc across the plates (Fig. 14-2)? The plateswill become electrically charged, and will reach a potential difference equal to the dcsource voltage. It won’t matter how big or small the plates are; their mutual voltage will al-ways be the same as that of the source, although, if the plates are monstrously large, itCopyright © 2002, 1997, 1993 by The McGraw-Hill Companies. Click here for terms of use.