Magnetic Force on Electron: Unanswered Mystery

AI Thread Summary
The magnetic force on an electron moving in a uniform magnetic field cannot be definitively calculated without knowing the angle between the electron's velocity and the magnetic field. The formula used, Fm = |q| v B sin θ, indicates that the force depends on this angle. The calculated force of 1.6x10^-14 N assumes a 90-degree angle, which maximizes the force, but this is not guaranteed. Therefore, without the angle θ, the exact magnetic force remains undetermined. Understanding the relationship between velocity, magnetic field strength, and angle is crucial for accurate calculations.
dcgirl16
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an electron moves within a uniform magnetic field of .2T at a speed of 5x10^5 m/s. What is the magnetic force on the electron?

I used Fm=qvBSin and got 1.6x10^-14N but the answer is that it can't be determined with this info why not?
 
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dcgirl16 said:
an electron moves within a uniform magnetic field of .2T at a speed of 5x10^5 m/s. What is the magnetic force on the electron?

I used Fm=qvBSin and got 1.6x10^-14N but the answer is that it can't be determined with this info why not?

Because you don't know the angle between the velocity of the electron and the magnetic field! You are right that the magnitude of the magnetic field is F_m = |q| v B sin \theta but without the angle \theta you can't find the answer. (how did {\em you} get an answer? I bet that you used an angle equal to 90 degrees!)

Patrick
 

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