(a) Calculate the capacitance needed to get an $RC$ time constant of $1.00\times 10^3\text{ s}$ with a $0.100\Omega$ resistor. (b) What is unreasonable about this result? (c) Which assumptions are responsible?

Video Transcript

This is College Physics Answers with Shaun Dychko. We're identifying the capacitance needed to get a time constant of one times ten to the three seconds with a 0.1 Ohm resistor. And the time constant is resistance times capacitance so divide both sides by R and we get C as tau over R. So that's one times ten to the three seconds divided by 0.1 Ohms which is 10 Kilo Farads or ten times to the three Farads. And such a large capacitor is unrealistically large and would not be reasonable to expect such a large time constant of ten to the three seconds given such a small resistance of only 0.1 Ohms.