Module 4
1. Module 4
1.15. Page 7
Module 4—Magnetic and Electric Fields in Nature and Technology
Lesson Summary
In this lesson you focused on the following essential questions:
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How is moving charge affected by a magnetic field?
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Which variables determine the magnitude of the magnetic force?
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How is the direction of the magnetic force determined?
When a charged particle moves perpendicularly to an external magnetic field, it exhibits uniform circular motion. The inward force is a magnetic force that is proportional to the product of the particle’s speed (perpendicular to the magnetic field), the magnitude of the particle’s charge, and the strength of the magnetic field in which it moves. Expressed mathematically it is
When the charged particle is moving at right angles to a magnetic field, the force exerted on the particle by the field is perpendicular to both the particle's velocity and the magnetic field. Therefore, to predict the direction of the magnetic force, you only need to know the direction of the particle’s velocity and the direction of the magnetic field.
The direction of the force acting on a negative particle can be determined by the left-hand rule for deflection. The direction of the force exerted on a positively charged particle moving in a magnetic field can be visualized by the right-hand rule for deflection.
A combination of the equation above and the appropriate hand rule can be used to determine the magnitude and direction of the magnetic force acting on any moving charged particle.