HW10soln - Physics 21 Fall 2007 Solution to HW-10...

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Physics 21 Fall 2007 Solution to HW-10 Electromagnetic velocity filter An ion source sends particles with velocity v along the + x axis. The particles encounter plates a distance d apart that generate a uniform electric field E in the + y direction. (A) A magnetic field in what direction will generate a force that cancels the electric force? (B) Find the magnitude of the magnetic field that will cancel the electric force. (C) How should you choose q and m to obtain the best possible velocity resolution? You want particles with the incorrect velocity to have the maximum possible deflection so that they will not go through the slit. The deviation will be maximum when the acceleration is a maximum. Since F=ma , and F=qE , a is max when F/m = qE/m is max. So for q/m as large as possible, make q large and m small. 27.1 A particle with charge - q moves with instantaneous velocity v = v x i + v y j . (A) What is the force exerted on this particle by a magnetic field B = B i ? Find the
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This note was uploaded on 02/29/2008 for the course PHYSICS 21 taught by Professor Hickman during the Spring '08 term at Lehigh University .

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