Proton Beam therapy (magnetic field)

AI Thread Summary
The discussion revolves around calculating the magnitude of a constant magnetic field required to deflect a proton beam at a specific velocity and radius. The relevant equation used is B = mv/er, where m is the proton mass, v is the velocity, e is the charge of the proton, and r is the radius of the arc. An initial calculation yielded an incorrect value of 7.515, while the correct answer is 0.47T. The error was identified as a potential miscalculation of input values. The final consensus confirms that the correct magnetic field strength is indeed 0.47T.
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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