Cracking the SAT Physics Subject Test

(Marvins-Underground-K-12) #1

The presence of the electric field creates a potential difference between the ends of
the rod. Since negative charge accumulates at the lower end (which we’ll call point
a) and positive charge accumulates at the upper end (point b), point b is at a higher
electric potential.


The potential difference Vba is equal to Eℓ and, since E = vB, the potential


difference can be written as vBℓ.


Now imagine that the rod is sliding along a pair of conducting rails connected at the
left by a stationary bar. The sliding rod now completes a rectangular circuit, and the
potential difference Vba causes current to flow.


The Skinny on
Induced Current
An induced current can be
created in two different
ways:


  1. Changing the size of a
    circuit in a stationary
    magnetic field

  2. Changing the magnetic
    field strength through a

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