Electronic Circuit Analysis

APPENDIX 321
The right-hand rule for determining the qirection of flux from a solenoid is illustrated in
Fig. A. S.7(d). When the solenoid is gripped with the right hand so that the fingers are pointing in the
direction of current flow in the coils, the thuplb points in the direction of the flux (Le., toward the N­
pole end of the solenoid).
Electromagnetic Induction
It has been demonstrated that a magnetic flux is generated by an electric current flowing in a conductor.
The converse is also possible; that is, a magnetic flux can produce a current flow in a conductor.
"­
"
Flux around ~
conductor
(a) All of the flux passes through the center of
the coil turn
----
....-
" .
"
----- ' .....
--,
~'"
(b) Side view of coil turn and flux
---------------
-~-
I~ ,i
(c) A soler1oid sets up a flux like a bar
magna
Fingers point in
current direction
(d) Right-hand rule for solenoid flux
direction
Fig. A. 5.7 In current-carrying coils, the magnetic lines of force around the conductors all pass
through the center of the coil.