Magnetism
Whenever electrical current flows, a measurable effect called
magnetism
is produced in
the vicinity of that current. For straight conductors, the magnetic field circles around the
current in a direction dictated by the
RightHand Rule
(
RHR
). There are many versions of
this rule, and the best one for this first
situation is to give the
thumbsup
sign
with the thumb extended in the
direction of the current. The fingers
then wrap in the direction that the
B
field
(magnetic field) lines encircle the
current. In fact, if you place a magnetic
compass near a wire, it will align with B.
The magnitude for such a current is given by
Ampère’s Law
, the magneticfield
equivalent of Gauss’s Law for electric fields. The equation is
B=
µ
₀
I
in
/
l
where
B
is the
magnetic field density measured in
teslas
(
T
),
µ
(“munought) is a constant called the
permeability of free space
(
4
π
×
10
⁻⁷
),
I
in
refers to the current within the
Amperian
surface
(which is just a circular loop this time), and
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '11
 Tibbets
 Current, Magnetism, Magnetic Field, RHR

Click to edit the document details