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Difficulty: MediumMagnetism Fundamentals

Two identical bar magnets are placed end-to-end on a workbench with their north poles facing each other across a narrow gap. Which of the following best describes the behavior of the magnetic lines of force in the space between these two poles?

  1. A
    The flux lines travel straight across the gap from one north pole into the other, creating an attractive force that pulls the magnets together.
  2. The flux lines curve away from each other without crossing, exerting lateral pressure that pushes the two poles apart.Answer
  3. C
    The flux lines cross one another in a grid pattern, turning the air gap into an electrically conductive pathway.
  4. D
    The flux lines accumulate in the air gap to store electrostatic potential energy in the same manner as a dielectric in a capacitor.

Answer

The flux lines curve away from each other without crossing, exerting lateral pressure that pushes the two poles apart.
Magnetic lines of force (flux lines) have two fundamental physical rules: they emerge outward from north poles into external space, and they can never intersect or cross. When two north poles face each other, the emerging flux lines are forced to deflect and curve away from each other into surrounding space. This lateral repulsion between parallel lines of force creates the physical repulsive force pushing the two like poles apart.

Step-by-Step Solution

1
Identify the polarity and fundamental rule of magnetic interaction.
Both facing ends are north poles, meaning they are like magnetic poles that inherently repel each other.
The fundamental law of magnetism states that like poles repel and opposite poles attract.
2
Determine the direction and properties of magnetic flux lines outside the magnets.
Magnetic flux lines emerge from north poles and seek south poles; flux lines never cross or intersect.
A magnetic field at any given point has a unique direction, making intersecting lines physically impossible.
3
Analyze the field line geometry in the gap between the two facing north poles.
The emerging lines of force from both north poles bend outward into surrounding space, exerting lateral repulsive pressure on one another.
Because lines of force running in the same direction repel each other and cannot enter a like pole, they diverge outward and create magnetic repulsion.

Key Concept

Magnetic Field Line Properties and Like-Pole Repulsion
Estimated Time:1m 0s
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Topics

Magnetism Fundamentals

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