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# A2 Physics A Turning points: Magnetic field question help

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Why bother with a post grad course - waste of time? 17-10-2016
1. Question
A beam of electrons moving at a speed of 2.8 × 10^7 ms−1passes through perpendicular electric andmagnetic fields without being deflected. The magnetic field has a flux density 3.2 × 10^−3 T.Calculate the strength of the electric field.

So I thought
Electric field force = magnetic field force
so for magnetic field:
F=Bev
F= (3.2 × 10^−3) * (1.60× 10^−19) * (2.8 × 10^7)
F= 1.4 × 10^−14

What am I doing wrong, I know it must be something dumb.
2. Nevermind, I got it now. Electric field strength is not force...
3. Did you get the answer?
4. (Original post by Improvement)
Yep, I managed to get it in the end

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