Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 21: Q77PE (page 778)

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

Short Answer

Expert verified
  1. Capacity is \(10000\;F\).
  2. If we know that the earth's capacity is finite, the capacity required is irrational.

Step by step solution

01

Definition of RC constant and resistance.

RC time constant: This measurement informs us how long it will take a cap to charge to a particular voltage level.

Anything that prevents current flow is referred to as "resistance" in this context.

02

Given Information.

  • \(RC\) time constant is: \(1.00 \times {10^3}{\rm{ }}s\)
  • Resistor: \(0.100 - \Omega \).
03

Step 3:Calculate the capacity needed.

a.

We can calculate the capacity needed to have a time constant of \({10^3}\;s\):

\(\begin{align}{}C = \frac{\tau }{R} = \frac{{{{10}^3}}}{{0.1}}\\C = 10000\;F\end{align}\)

Hence, Capacity is \(10000\;F\).

04

Explanation of solution.

(b)

Unreasonable is the capacity needed if we know that earth's capacity is \(1F\).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Find the resistance that must be placed in series with a \(10.0 - \Omega \) galvanometer having a \(100 - \mu A\) sensitivity to allow it to be used as a voltmeter with:

(a) a \(300 - V\) full-scale reading, and

(b) a \(0.300 - V\) full-scale reading.

An 1800-W toaster, a 1400-Welectric frying pan, and a 75-Wlamp are plugged into the same outlet in a 15 A,120 Vcircuit. (The three devices are in parallel when plugged into the same socket.) (a) What current is drawn by each device? (b) Will this combination blow the 15-A fuse?

Figure 21.55 shows how a bleeder resistor is used to discharge a capacitor after an electronic device is shut off, allowing a person to work on the electronics with less risk of shock. (a) What is the time constant? (b) How long will it take to reduce the voltage on the capacitor to 0.250%(5% of 5%) of its full value once discharge begins? (c) If the capacitor is charged to a voltage V0 through a 100-Ω resistance, calculate the time it takes to rise to 0.865V0 (This is about two-time constants.)

(a) What is the unknownemfxin a potentiometer that balances whenRxis 10.0Ω , and balances when role="math" localid="1656393398590" Rsis 15.0Ωfor a standard 3.000-V emf? (b) The sameemfxis placed in the same potentiometer, which now balances when Rsis 15.0Ω for a standard emf of 3.100-V . At what resistanceRxwill the potentiometer balance?

(a) What is the potential difference going from point \(a\) to point \(b\) in Figure \(21.47\)? (b) What is the potential difference going from \(c\)to \(b\)? (c) From \(e\) to\(g\)? (d) From \(e\) to \(d\)?
See all solutions

Recommended explanations on Physics Textbooks

Electric Charge Field and Potential

Read Explanation

Particle Model of Matter

Read Explanation

Conservation of Energy and Momentum

Read Explanation

Scientific Method Physics

Read Explanation

Astrophysics

Read Explanation

Rotational Dynamics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free