Iron core
Lines of
magnetic flux
FIGURE 10. The unit inductance the henry (symbol H), commemorate the
work the American physicist Joseph Henry (1797–1878), and circuit is
said possess inductance henry when emf volt induced
in the circuit current changing the rate ampere per second. The collapsing magnetic flux induces emf into
the coil and this voltage appears across the switch contacts.10
An inductive coil choke.Alternating current theory and electrical machines
205
When the switch opened the current stops flowing and, therefore, the
magnetic flux collapses.
. The starter lamp switches and off very quickly,
causing rapid current changes which induce large voltage across the tube
electrodes sufficient strike arc the tube.11. The two coils
in this case are said possess mutual inductance, shown Fig.
Fluorescent light fittings contain choke inductive coil series with the
tube and starter lamp. 10.
Whentwoseparatecoilsareplacedclosetogether,astheyareinatransformer,
a current one coil produces magnetic flux which links with the second
coil. The effect is
known self-inductance, just inductance, and one property any
coil.11
Mutual inductance between two coils.
FIGURE 10. This induces voltage the second coil and the basic principle of
the transformer action which described later this chapter
