Magnetic Field Lines Quiz

Plotting Magnetic Field Lines

• To plot magnetic field lines, follow this procedure:
  • Place a plotting compass at the point where you want to start the line. The compass needle's north pole should point along the line.
  • Draw an arrow in the direction the north pole points.
  • Move the compass so the south pole points to the end of the arrow you just drew.
  • Draw another arrow where the north pole now points.
  • Repeat these steps, moving the compass and drawing arrows until you reach the desired end point.
  • Connect the arrows with a smooth curve. This creates the magnetic field line.
  • Different field lines can be created by starting at different points near the magnet's north pole.

Geometric Properties of Magnetic Field Lines

• Magnetic field lines are smooth curves that always start at a north pole and end at a south pole.
• Arrows on the lines indicate the direction of the force a north pole would experience in that area.
• South poles experience the opposite force.
• Magnetic field lines are often called lines of flux because they resemble the flow of water, although no actual fluid is involved.
• Field lines never cross. This is because, at any given point, a plotting compass can only point in one direction.
• If extrapolated, field lines meet at the poles.

Exercise 3.5

• If the south pole of a plotting compass points toward the east, then the magnetic field's direction at that point is west.

Lines of Force Usefulness

• Field lines show the direction of the field in a region.
• Closer lines mean a stronger field.