Physlet Illustration: Motion and Induced Current

 

 

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This simulation shows a top view of four wires and a galvanometer.   There is a constant magnetic field passing through these wires.  Determine the direction of this magnetic field by click-dragging the black wire back and forth and observing the galvanometer reading.  Remember that current flowing into the + terminal, i.e., counterclockwise, will deflect the meter to the right.   You may change the strength of the magnetic field between 0 and 2 Gauss.

Hints:

  1. Which direction is the field of a North pole?  Which direction is the field of a South pole?  
  2. Choose a direction for the normal, either into or out of the rectangle (screen).  Use the right-hand rule to determine the direction of the current.
  3. If the magnetic field is out of the rectangle (screen) and you drag the wire to make the rectangle smaller, does the flux increase or decrease?  
  4. Which direction is the induced current if the flux increases?  Don't forget the minus sign in Faraday's law.

Reference

See Walker, Section 23-3 & 23-4

Illustration written by Mario Belloni and Modified by Chuck Niederriter