FIGURE: http://postimg.org/image/co8itenhl/ The figure shows a 60-Hz ac laborato

Question

FIGURE: http://postimg.org/image/co8itenhl/

The figure shows a 60-Hz ac laboratory setup for trouble-shooting the 20 ?F capacitor, which has been around a while and needs to be checked before being used.

(a) If the ammeter reads 0.25 A and the voltmeter reads 120 V, what can you say about the capacitor?

(b) Now suppose we put another suspicious 10 ?F capacitor across (in parallel) the first and find that the fuse blows every time the switch is closed. What would you then conclude?

Answers with EXPLANATIONS please :) Thanks!

Explanation / Answer

a)Ammeter reading=0.25A=I

Voltmeter reading=120V=V

Impedance=1/sC=1/60C=120/0.25=480=V/I

1/60C=480C=1/60*480=34?F.Hence capacitance of capacitor is 34?F.

b)Fuse blew up which means current>1.5A

Impedance<120/1.5=80

Since they are in // capacitances get added

1/60*(C+10)<80

C+10?F>1/4800F

C+10>208

C>198?F

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