Proton Beam therapy (magnetic field)

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SUMMARY

The discussion focuses on calculating the magnitude of a constant magnetic field required to deflect a proton beam at a velocity of 1.8 x 108 m/s through a circular arc of radius 4 meters. The relevant equation used is B = mv/(er), where m is the mass of the proton (1.67 x 10-27 kg), e is the charge of the proton (1.6 x 10-19 C), and r is the radius of the arc. The correct calculation yields a magnetic field strength of 0.47 Tesla, confirming the accuracy of the equation and values used.

PREREQUISITES
  • Understanding of classical mechanics, specifically circular motion.
  • Knowledge of electromagnetism, particularly the Lorentz force law.
  • Familiarity with the properties of protons, including mass and charge.
  • Ability to manipulate and solve algebraic equations involving physical constants.
NEXT STEPS
  • Review the derivation of the Lorentz force and its application in magnetic fields.
  • Explore the concept of circular motion in charged particles within magnetic fields.
  • Investigate the implications of magnetic field strength on particle trajectories in accelerators.
  • Learn about the applications of proton beam therapy in medical physics.
USEFUL FOR

Students and professionals in physics, particularly those studying electromagnetism and particle dynamics, as well as medical physicists involved in proton beam therapy applications.

tombroz
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Homework Statement


A beam of protons with v=1.8x10^8 are deflected 90 degrees by a constant magnetic field. The trajectory of the beam has a circular arc with a radius of 4m.

I am asked to find the magnitude of the constant magnetic field.

Homework Equations



I know that r=mv/eB. When solving for B the equation is B=mv/er. Right?
m=1.67x10-27
v=1.8x108
e=1.6x10-19
r=4

The Attempt at a Solution



This gives me 7.515 for the magnitude of the magnetic field. The correct answer is 0.47T.
Did I start with the wrong equation?
 
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Welcome to PF.

You may have entered a number wrong. Using your values I get 0.47T as well.
 
Ahh... I see.

That was easy. Thanks!
 

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