Teaching Minds-On Experiments on Electromagnetism in Secondary Schools
Exploring the magnetic effects of an electric current
We place two or more compasses around a straight wire carrying an electric current (under, above, next to).
The needle of the compass: turns until it sits in an orthogonal
direction with respect to the wire. The direction indicated by the
needle is the opposite for the compasses placed beneath the wire, with
respect to those placed above the wire.
If we reverse direction of the current in the wire the orientation of
the needles is reversed in the compasses placed above and below the
The magnetic effect of an electrical current is manifested on a
perpendicular plane in the direction of the current. The magnetic field
produced by a current extends above and below the cable. The direction
of this is fixed when the direction of the current is fixed.
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