If we place a wire within a uniform exterior magnetic field ($B_x$) that's perpendicular to it's length, and allowed current to flow withing the that conductive medium, there is another magnetic field generated from that wire ($B_w$). There is a Lorentz force as well, however, due to the $B_w$ existing with $B_x$ would they add or subtract from the net strength of each field?


enter image description here

The orange lines is of the exterior magnetic field, wanted to illustrate it in the most important views(right & top).

As a result of the magnetic field, there is a Lorentz force, would $B$ in the formula be only $B_x$? Why wouldn't it be ($B_x$ - $B_s$) or ($B_x$ + $B_s$)? Likewise, if the wire was able to accelerate in the the magnetic field, the induced motional EMF's $B$ be the same?


1 Answer 1


B should remain since Magnetic field is added in upper part and equally subtracted in lower part.

Hint: Wire does not experience its own magnetic force.

If you let wire to accelerate in $B$ freely , it won't give any magnetic field.. So, no current flow in wire. Hence EMF is induced in opposite direction.

  • $\begingroup$ I've adjusted the diagram, also,the magnetic field is uniform. I don't understand how and why it would be added in the upper part and subtracted in the lower part equally? Shouldn't they be the same at all points? $\endgroup$
    – Pupil
    Commented Feb 7, 2016 at 6:00
  • 1
    $\begingroup$ In upper part both magnetic field are towards right. So, they are added. In lower part they are opposite in direction, so are subtracted. $\endgroup$ Commented Feb 7, 2016 at 7:11

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