Assertion A charged particle moves perpendicular to a...

Name: Problem 41, Chapter 19: Master Resource Book in JEE Main Physics
Uploaded: 2022-01-30T16:45:45-08:00
Duration: 1 min 43 s
Channel: Supratim Pal
Description: Assertion A charged particle moves perpendicular to a magnetic field. Its kinetic energy remains constant, but momentum changes. Reason Force acts on the moving charged particles in the magnetic field.

Assertion A charged particle moves perpendicular to a magnetic field. Its kinetic energy remains constant, but momentum changes. Reason Force acts on the moving charged particles in the magnetic field.

Key Concepts

Magnetic Force (Lorentz Force)

The magnetic force, also known as the Lorentz force, acts on a moving charged particle when it enters a magnetic field. This force is always perpendicular to both the velocity of the charged particle and the magnetic field, resulting in a force direction that continually changes relative to the particle's motion. This fundamental concept underlies much of classical electromagnetism and is central to understanding how charged particles behave in magnetic fields.

Work Done by Magnetic Forces

A key concept in electromagnetism is that magnetic forces do no work on moving charged particles. Since the force is always perpendicular to the direction of motion, it does not change the speed of the particle. This means that while the particle's trajectory (direction of momentum) may be altered, its kinetic energy remains constant, illustrating the principle that work requires a component of force in the direction of displacement.

Change in Momentum Direction

Even though magnetic forces do not change the magnitude of a charged particle’s velocity, they alter the direction of the momentum vector. This results in a change in the momentum of the particle, despite the kinetic energy remaining unaltered. The momentum's directional change is due to the centripetal nature of the magnetic force, which continuously redirects the particle's motion without influencing its speed.

Transcript

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