|
The coil opposes the flow of ac current, as a resistor does in a dc circuit.
This
opposition
is
called
inductive
reactance,
XL. It is measured in ohms. Ohm's Law can be applied, as in the top formula.
The
bottom
formula
shows
how
inductive
reactance
is
calculated.
f is the frequency of the applied voltage, and L is the value of the coil in Henries.
It can be seen from this formula that the value of
XL goes up as the frequency increases. It also goes up if the value of the coil increases.
This means that as the value of L or f increases, the opposition to the flow of ac
current
increases,
and the
lamp
will
glow
less. |
