# I Determine voltage from a conductor in magnetic field

1. Apr 15, 2016

### BBruyne

Hi,

I would like to know how to get the potential difference due to a constant local magnetic field acting on a wire moving at a constant speed perpendicular to the field. What is the link between F = q v ∧ B and the actual difference of potential in the circuit ? How to determine the induced electric field ? I have attached an image to illustrate it.

Thank you,

Bbruyne

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2. Apr 15, 2016

### ZapperZ

Staff Emeritus
3. Apr 16, 2016

### BBruyne

Thanks for the link, very nice website. I am learning Faraday's law and I am trying to link motional emf to his law. I do understand that a squared loop of wire of length l moving with a velocity v into a stationnary magnetic field B will experience a Lorentz force and this force will induce an emf. From emf = l v∧B, with a bit of manipulation, we arrive to emf = dΦ/dt. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.html#c3

That means that if the loop of wire is not moving but we approach a magnet into the loop, we get an induced emf. How can we justify this with the initial idea emf = l v∧B. We could say that the loop is moving relatively to the magnet but, it is moving in a parallel direction to the magnetic field of the magnet, thus v∧B = 0.