Grr I've been trying to figure this out and i'm just getting frustrated because I can't find any help in my book...(adsbygoogle = window.adsbygoogle || []).push({});

A long straight wire carries a current of 20 A. An electron, traveling at 2X10^7 m/s, is 3 cm from the wire. What force (magnitude and direction) acts on the electron if the electron's velocity is directed toward the wire?

given: ok, so i know that the wire is long and straight (so i know how its magnetic field will act) and i know the current in it..I also know the charge on the electron..it's velocity and its distance from the wire...

I'm supposed to find the magnitude and direction of the force acting on the electron... Ok- so let's say the wire is coming out of the page- i know the magnetic field will be counter-clockwise so in that case, the force would be "up" (perpendicular to the current.) I can find the force on the electron due to the magnetic field at it's current point using the equation B= (uoI/2pi r)

where uo is the constant. I really dont know though how to adjust this for the charge on the electron or the velocity. I know how a charge would act in a uniform magnetic field and i remember that when a charged particle moves it creates an electric field- so i know if a electron moves from infinity to any location close to a proton or electron i can find the force...

gah i cant figure it out! please help!

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# Homework Help: This should be easy

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