PhysicsQuest: Electromagnetic Induction

Induced Currents

Introduction

Until now we have considered electric and magnetic interactions as separate phenomena. Charges make electric fields, and electric fields affect charges. Moving charges make magnetic fields, and magnetic fields affect moving charges. Now we will see another fundamental aspect of the relationship between the two kids of fields. It turns out that a time-varying magnetic field can produce an electric field! We can say that a time-varying magnetic field “induces” an electric field, and we call this phenomenon “magnetic induction.” In this PhysicsQuest you will be exploring various aspects of magnetic induction.

Instructions

  • Visit the links provided for each section and neatly write your answers to the questions.
  • You must use your own words. Do not copy and paste to your paper!

Section 1: Magnetic Induction

Links for this section:

  1. According to Faraday’s Law, what happens when you change the magnetic flux passing through a coil of wire?
  2. What are 4 ways to change the magnetic flux passing through a coil of wire?
  3. Try it! Take the aluminum tube (it’s not magnetic) and drop the magnet and the non-magnet through it.  What happens?  Why does this happen?

Section 2: Self Inductance

Links for this section:

  1. What is “self-inductance”?
  2. What is an “inductor”?
  3. Describe the differences in behavior between a capacitor and an inductor in a circuit.
  4. What are some applications of inductors in circuits?

Section 3: Physics in Action

  1. Using this Java applet (which won’t work on iDevices), build the pictured circuit consisting of 3 batteries, a switch, 2 light bulbs in parallel, and 1 inductor.
      1. Describe what happens to the current through the batteries and the bulbs, and describe what happens to the brightness of the bulbs:
        1. immediately after closing the switch.
        2. a long time after closing the switch.
        3. immediately after opening the switch.
        4. a long time after opening the switch.
      2. Explain how the inductor is causing any changes from normal circuit behavior.

    LR Circuit

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