(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A long, straight wire carries a current of 2.5 A. An electron is traveling in the vicinity of the wire. At the instant when the electron is 4.5cm from the wire and traveling with a speed of 6.00 X 10^4 m/s directly toward the wire, what are the magnitude and direction (relative to the direction of the current) of the force that the magnetic field of the current exerts on the electron?

2. Relevant equations

F = qv X B

for an infinitely long straight wire:

B = (2x10^-7)(I)/r

so...

F = (qv) X (2x10^-7)(I)/r

3. The attempt at a solution

I = 2.5A

r = .045m

v = 6x10^4 m/s

q = -1.6X10^-19 C

The answer is F = 1.07 X 10^-19 N. i got that right. but how do i know whether it is going with the current or against the current?

i think all i know is magnetic field, current and direction of electron are all perpendicular to each other. The answer says it goes WITH the current, but i dont understand how they got that

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# Homework Help: Force, magnetic field, current, long straight wire

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