Calculating Electron Velocity and Orbit in Crossed Electric and Magnetic Fields

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SUMMARY

The velocity of a beam of electrons passing through crossed electric and magnetic fields of 6.8 kV/m and 4.9 mT is calculated using the formula v = E/B, resulting in a velocity of 1.3877 x 106 m/s. To determine the radius of the electron's orbit when the electric field is turned off, one must apply the centripetal force equation, which relates the magnetic force acting on the charged particle to the required centripetal force for circular motion. The magnetic force is given by F = qvB, where q is the charge of the electron.

PREREQUISITES
  • Understanding of electromagnetism principles, specifically electric and magnetic fields.
  • Familiarity with the equations of motion for charged particles in magnetic fields.
  • Knowledge of the relationship between electric field strength, magnetic field strength, and velocity.
  • Basic calculus for deriving the radius of circular motion from forces.
NEXT STEPS
  • Study the derivation of the centripetal force equation for charged particles in magnetic fields.
  • Learn about the Lorentz force and its application in charged particle motion.
  • Explore the concept of cyclotron motion and its relevance in particle physics.
  • Investigate practical applications of crossed electric and magnetic fields in devices like mass spectrometers.
USEFUL FOR

Students studying electromagnetism, physics educators, and professionals working in fields involving charged particle dynamics, such as accelerator physics and plasma physics.

Angie K.
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Homework Statement



What is the velocity of a beam of electrons that go undeflected when passing through crossed electric and magnetic fields of magnitude 6.8 kV/m and 4.9 mT, respectively?

What would be the radius of the electron's orbit if the electric field were turned off?

Homework Equations



v = E/B

The Attempt at a Solution



I got the first part by using the equation above. (I converted the measurements because I'm looking for m/s). So 6.8 kV/m is 6800 V/m and 4.9 mT is .0049T.

v = E/B
v = (6800V/m)/(.0049T)
v = 1.3877*10^6 m/s

For the second part, I am a bit confused as to how to find the radius (which equation to use?).
 
Physics news on Phys.org
What force acts on a charged particle in magnetic field? That force provides the centripetal force for the circular motion.
 

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