Question

A metal bar, pivoted at one end, oscillates freely in the absence of a magnetic field. But when it oscillates between the poles of a magnet, its oscillations are quickly damped. Why? (Such magnetic damping is used in a number of practical devices.)

Name: Problem 94, Chapter 25: Conceptual Physics
Uploaded: 2019-09-08T20:43:00-08:00
Duration: 1 min 29 s
Channel: Averell Hause
Description: A metal bar, pivoted at one end, oscillates freely in the absence of a magnetic field. But when it oscillates between the poles of a magnet, its oscillations are quickly damped. Why? (Such magnetic damping is used in a number of practical devices.)

   A metal bar, pivoted at one end, oscillates freely in the absence of a magnetic field. But when it oscillates
between the poles of a magnet, its oscillations are quickly damped. Why? (Such magnetic damping is used in a number of practical devices.)

Conceptual Physics

Paul G. Hewitt 12th Edition

Chapter 25, Problem 94

Instant Answer

Solved by Expert Averell Hause

09/08/2019

Step 1

This movement in a magnetic field induces a current in the metal bar. This is due to Faraday's law of electromagnetic induction, which states that a change in the magnetic environment of a coil of wire will induce a voltage in the wire. In mathematical terms, this Show more…

Show all steps

Thanks for your feedback!

A metal bar, pivoted at one end, oscillates freely in the absence of a magnetic field. But when it oscillates between the poles of a magnet, its oscillations are quickly damped. Why? (Such magnetic damping is used in a number of practical devices.)

Play audio

Feedback

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Electromagnetic Induction

This is the process by which a changing magnetic field induces an electric current in a conductor. When a metal bar oscillates through a magnetic field, the motion causes changes in the magnetic flux through the metal, leading to the production of currents within it.

Eddy Currents

These are loops of electric current induced within conductors by a changing magnetic field. The induced eddy currents create their own magnetic fields which oppose the original change causing them, and this opposition results in forces that resist the motion of the metal bar.

Lenz's Law

This law states that the direction of the induced currents is such that their magnetic effects oppose the change in magnetic flux that produced them. In the context of a metal bar oscillating in a magnetic field, Lenz's Law explains why the eddy currents act to damp the motion of the bar, effectively reducing its oscillations over time.

Please give Ace some feedback