Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 21: Q4CQ (page 771)

Why is the power dissipated by a closed switch, such as in Figure 21.43, small?

Short Answer

Expert verified

Due to the low resistance of a closed switch, the power dissipated is little.

Step by step solution

01

Definition of voltage

Voltage: It's the difference between two points’ electric potentials.

02

Given

Resistance of the switch when closedRclosed=0Ω

Resistance of switch when openRopen=∞Ω

Emf of the battery isE

The internal resistance of the battery isr

External resistance connected in series with the battery isR

Current in the circuit when the switch is closedlclosed

Current in the circuit when the switch is openlopen

03

Finding why the power dissipated by the closed switch is small

The power dissipated is given :

P=lclosed2RclosedP=lclosed20ΩP=0W

Resistance is directly proportional to power. As a result, the lower the resistance, the lower the power dissipated.

Therefore, the resistance of a closed switch is so low, that the power dissipated is little.

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

Show that if two resistors R1and R2are combined and one is much greater than the other (R1>>R2): (a) Their series resistance is very nearly equal to the greater resistance R1(b) Their parallel resistance is very nearly equal to smaller resistanceR2 .

If a potentiometer is used to measure cell on the order of a few volts, why is it most accurate for the standard to be the same order of magnitude and the resistances to be in the range of a few ?

(a) Given a48.0-v battery and24.0-Ω and96.0-Ωresistors, find the current and power for each when connected in series. (b) Repeat when the resistances are in parallel.

Suppose you measure the terminal voltage of an1.585-V alkaline cell having an internal resistance of0.100Ωby placing arole="math" localid="1656394302991" 1.00-kΩvoltmeter across its terminals. (See Figure 21.54.) (a) What current flows? (b) Find the terminal voltage. (c) To see how close the measured terminal voltage is to the emf, calculate their ratio.

Electric fish generate current with biological cells called electro-plaques, which are physiological emf devices. The electro-plaques in the South American eel are arranged in \(140\) rows, each row stretching horizontally along the body and each containing \(5000\) electro-plaques. Each electro-plaque has an emf of \(0.15{\rm{ }}V\) and internal resistance of \(0.25{\rm{ }}\Omega \). If the water surrounding the fish has resistance of \(800{\rm{ }}\Omega \), how much current can the eel produce in water from near its head to near its tail?
See all solutions

Recommended explanations on Physics Textbooks

Magnetism

Read Explanation

Nuclear Physics

Read Explanation

Famous Physicists

Read Explanation

Electrostatics

Read Explanation

Energy Physics

Read Explanation

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