College Physics (7th Edition)

Published by Pearson
ISBN 10: 0-32160-183-1
ISBN 13: 978-0-32160-183-4

Chapter 18 - Basic Electric Circuits - Learning Path Questions and Exercises - Conceptual Questions - Page 652: 15

Answer

During the charging of the capacitor, its charge as a function of time is :- $q=q_{0}(1-e^{-\frac{t}{T}})$, $T$ being the time constant After 1 time constant, T, has elapsed the charge is $q=q_{0}(1-e^{-1})\approx 0.632q_{0}$, so time it takes to charge up to $0.25q_{0}$ is less than 1 time constant. When discharging, the capacitor's charge is $q=q_{0}e^{-\frac{t}{T}}$. After 1 time constant, the charge is $q=q_{0}e^{-1}=0.368q_{0}$, so the time to discharge to $0.25q_{0}$ is more than 1 time constant.

Work Step by Step

During the charging of the capacitor, its charge as a function of time is :- $q=q_{0}(1-e^{-\frac{t}{T}})$, $T$ being the time constant After 1 time constant, T, has elapsed the charge is $q=q_{0}(1-e^{-1})\approx 0.632q_{0}$, so time it takes to charge up to $0.25q_{0}$ is less than 1 time constant. When discharging, the capacitor's charge is $q=q_{0}e^{-\frac{t}{T}}$. After 1 time constant, the charge is $q=q_{0}e^{-1}=0.368q_{0}$, so the time to discharge to $0.25q_{0}$ is more than 1 time constant.
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