Question

a straight wire of length tm is oriented east-west and is in a magnetic field b pointing north. the wire ismoving downward at a constant speed v. if the resistance of the rod is r, what is the current through the rod?

Answer 1

I = V / r where I is current in rod with resistance r

V = W / Q work / unit charge

I = W / (r Q) combining equations

W = F x where F is force on wire and x distance traveled

I = F x / (r Q)

I = I L B x / (r Q) where I L B is force on moving wire

I = L B x / (t r) since I = Q / t charge / time

I = L B v / r since x is speed of moving wire

If tm is length of wire then

I = tm B v / r in terms of given quantities