A 30.0-mH inductor has a reactance of 1.70 k. (a) What is the frequency of the a

Question

A 30.0-mH inductor has a reactance of 1.70 k.

(a) What is the frequency of the ac current that passes through the inductor? Correct: Your answer is correct. Hz

(b) What is the capacitance of a capacitor that has the same reactance at this frequency? Incorrect: Your answer is incorrect. F

I need help with part B. I got 1.0E-8 but the system was grading it as incorrect. Thanks for your help.

(c) The frequency is tripled, so that the reactances of the inductor and capacitor are no longer equal. What is the new reactance of the inductor? Correct: Your answer is correct. k

(d) What is the new reactance of the capacitor? Correct: Your answer is correct. k

Explanation / Answer

a) The reactance of an inductor is given by

X = w L = 2 pi f L

thus the frequency is

f = X / 2 pi L = 1700/(2*pi*30E-3) = 9023.36 Hz

b) The reactance of a capacitor is

X = 1 / 2 pi w C

solving for C we get

C = 1 / (2*pi*X) = 1 / (2*pi()*9023.36*1700) = 0.000000001038 F

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