A magnetic field deflects an electron beam, but work on the beam

Click For Summary

Discussion Overview

The discussion centers on the interaction between a magnetic field and an electron beam, specifically addressing why a magnetic field does not perform work on the beam despite causing deflection. The scope includes conceptual understanding of forces and energy in the context of electromagnetism.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • One participant states that a magnetic field does not change the kinetic energy of the electron beam, only its direction.
  • Another participant elaborates that the magnetic force is always perpendicular to the electron's velocity, which implies that no work is done since there is no displacement in the direction of the force.
  • A later reply expresses gratitude for the clarification provided.

Areas of Agreement / Disagreement

Participants appear to agree on the principle that a magnetic field does not do work on the electron beam due to the nature of the magnetic force and its relationship to velocity.

Contextual Notes

The discussion touches on the frame dependence of kinetic energy, which may introduce additional complexity not fully explored in the conversation.

Who May Find This Useful

Individuals interested in electromagnetism, particularly those seeking to understand the principles of forces acting on charged particles.

DevilDoc
Messages
5
Reaction score
0
A magnetic field deflects an electron beam, but it can not do any work on the beam. Why? :confused:
 
Physics news on Phys.org
It does not change the kinetic energy, only the direction.

The gotcha is that kinetic energy is frame dependent, but this feature is probably not of primary interest to you at this point.
 
Another way of saying what turin just said is that the magnetic force is always perpendicular to the electron's velocity: No work is done since there is no displacement in the direction of the force.
 
thank you for the help. :)
 

Similar threads

Undergrad Charge movement relative to magnetic field frame dependence/invariance
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Does electron beam in empty space generate magnetic fields?
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Question on Hall Effect and magnetic force
  • · Replies 2 ·
Replies
2
Views
2K
Graduate New magnetic field imaging technology with 100 nm resolution
  • · Replies 1 ·
Replies
1
Views
997
High School Why does my LC circuit not oscillate its energy between Electric & Magnetic fields?
  • · Replies 152 ·
6
Replies
152
Views
8K
High School How does a compass know that it is in a magnetic field?
  • · Replies 16 ·
Replies
16
Views
2K
High School How is the magnet being affected in this diamagnetic application?
  • · Replies 2 ·
Replies
2
Views
1K
Undergrad Fundamental - Magnetic fields generated by moving electrons
  • · Replies 23 ·
Replies
23
Views
5K
Undergrad Collimation of an Electron Beam by the Anode of a CRT
  • · Replies 6 ·
Replies
6
Views
3K
High School Why does a magnet attract metal objects?
  • · Replies 2 ·
Replies
2
Views
2K