Question

QUESTION 3 Assume you have a capacitor with an initial potential difference of 100 V that is discharged through a resistor when a switch between them is closed at t=0. Att= 10.0s, the potential difference across the capacitor is 1.00 V and its time constant RC is 2.17 sec. What is the potential difference V(t) across the capacitor at t= 17.0 s? 0.0396 V 0.0309 V 0.0456 V 0.0412 V QUESTION 4 The capacitance (size) of the capacitor is a measure of how much charge it can hold for a given voltage? True False

Answer 1

Ques 3

Discharging of a capacitor is given by

$V_C = V_S e^{-\frac{t}{RC}}$

So, at t= 10 s

$V_{10} = V_S e^{-\frac{10}{RC}}$

and at t = 17 s

$V_{17} = V_S e^{-\frac{17}{RC}}$

dividing the two

$\frac{V_{17}}{V_{10}} = e^{-\frac{7}{RC}}$

$\frac{V_{17}}{V_{10}} = e^{-\frac{7}{2.17}}$

$\frac{V_{17}}{V_{10}} = 0.0397$

$V_{17}= 0.0397 \times 1$

Ques 4

ture