Electron Motion in a Long Solenoid

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SUMMARY

The discussion focuses on calculating the current in a long solenoid with 100 turns/cm, where an electron moves in a circular path of radius 0.022 cm at a speed of 0.048c. The relevant equations include the magnetic field B of the solenoid, defined as B = μ*n*I, and the force on the electron, f = m*v²/r = q*v*B. A common error identified was using the mass of a proton instead of an electron, which led to incorrect current calculations. The correct current value, after adjustments, is confirmed to be accurate.

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Homework Statement



A long solenoid has 100 turns/cm and carries a current i. An electron moves within the solenoid in a circle of radius 0.022 cm perpendicular to the axis of the solenoid. The speed of the electron is 0.048c (c is the speed of light).

Homework Equations



f = m*v^2/r = q*v*B
B of a solenoid = u*n*I
where n = number of turns per meter
u = 4*pi*10^7


The Attempt at a Solution



so B = mv/(r*q) = u*n*I
I = mv/(r*q*u*n)
I = 5436.9 is not correct
 
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your working looks fine to me... But I got a different value for the current when I plugged the numbers in. Maybe that's where the problem is.
 
I was using the mass of a proton instead of an electron. replugged the numbers, and it works now!
thanks!
 

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