Engineering Board Exam Reviewer · Time Response of Reactive Circuits · hard
An RC circuit has a time constant of 0.1 s. After the switch connects it to a dc source, how long does the (initially uncharged) capacitor take to reach half of the source voltage?
- 50 ms
- 69.3 ms
- 100 ms
- 144 ms
Answer
B. 69.3 ms
Solution
0.5V=V(1-e-t/ ) e-t/ =0.5 t= 2=(0.1)(0.693)=69.3 ms.
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