Capacitors in parallel

Chapter Capacitors in parallel

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

  • 1/C210,000. Therefore, 1/C1,00010,00011,000, and C0. 000091 µF. Thisnumber is a little awkward, and you might rather say it’s 91 pF.In the above problem, you could have chosen pF to work with, rather than µF. In either case, there is some tricky decimal placement involved. It’s important to double-check calculations when numbers get like this. Calculators will take care of the decimalplacement problem, sometimes using exponent notation and sometimes not, but a cal-culator can only work with what you put into it! If you put a wrong number in, you willget a wrong answer, perhaps off by a factor of 10, 100, or even 1,000.Problem 11-3Five capacitors, each of 100 pF, are in series. What is the total capacitance?If there are n capacitors in series, all of the same value so that C1C2C3 . . . Cn,the total value C is just 1/n of the capacitance of any of the components alone. Becausethere are five 100-pF capacitors here, the total is C100/520 pF.Capacitors in parallelCapacitances in parallel add like resistances in series. That is, the total capacitance isthe sum of the individual component values. Again, you need to be sure that you use thesame size units all the way through.If two or more capacitors are connected in parallel, and one of the components ismuch, much larger than any of the others, the total capacitance can be taken as simplythe value of the biggest one.Problem 11-4Three capacitors are in parallel, having values of C10.100µF, C2,0.0100µF, andC3 0.00100µF, as shown in Fig. 11-4. What is the total capacitance?Capacitors in parallel20311-4Capacitors in parallel.Just add them up: C0.1000.01000.001000. 111000. Because the valuesare given to three significant figures, the final answer should be stated as C0.111µF.Problem 11-5Two capacitors are in parallel, one with a value of 100 µF and one with a value of 100 pF.What is the effective total capacitance?