PB_00  Capítulo 5  Análise de Fase  Página 5035
traduzido do livro: https://ntrs.nasa.gov/citations/19780078298
When a resistor is connected across a
generator, the current (I) will be in phase with the voltage (V) as
shown in view A. If the resistor is now replaced by a coil, the current
will no"longer be in phase with the voltage. The coil as you have seen
has both resistance and inductance (L). The inductance in turn is
expressed as the inductive reactance (XL) which you have learned is
determined by the inductance (L) and by the frequency applied to the
coil. (XL = 6.28 f).
In some cases, the inductive reactance (XL) is so much greater than the
coil's resistance that we can disregard the resistance. Under these
conditions, it can be shown that the current (I) lags the voltage (V)
by 90 degrees as shown in view B. It can also be shown that when the
resistance is a significant value (views C and D) the current will lag
the voltage by a value less than 90 degrees. The current lag shown in
view D reresents the effect of both the coil's inductance reactance and
the resistance. A change in either value will change the lag between
the current and the voltage.
If a change
in the coil's magnetic field is made by the presence of a specimen,
will the lag between the current and the voltage:
......
Change.
...... Remain the same.
ÍNDICE
