Quiz 7
The power factor for a capcitor is
0
The power factor for an inductor is
0
The power factor for a resistor is
1
An emf source that reverses polarity periodically:___ voltage source
AC
In a resistor, the current leads the voltage.
False
The time constant for an R-L circuit is
L/R
Maximum power delivered by the source occurs at the resonant frequency. In this state, the impedance Z =
R
The time constant for an R-C circuit is
RC
___ occurs when inductive reactance equals capacitive reactance.
Resonance
In an inductor, the current lags the voltage.
True
In general circuits with R, L, and C, the phase angle is
between -90° and +90°
As frequency decreases, inductive reactance
decreases
When current in a coil decreases, the energy stored in the magnetic field around it
decreases
In a capacitor, the current lags the voltage.
false
The unit of inductance is called the___ with symbol
henry; H
The quantity that gives an Ohm's Law-like relationship between voltage and current in general R-L-C circuits:
impedance
As frequency decreases, capacitive reactance
increases
When the charge on a capacitor increases, the energy stored in the electric field around it
increases
A measure of the emf produced in a coil due to changes in the current flowing through another coil.
mutual inductance
The henry is equivalent to
omeg-s & V-s/A
Power loss in a circuit equals VI cos ϕ . The cos ϕ term is called the
power factor
In a mutual inductance system, the coil attached to the power source is called the _____ coil. The other coil is called the____ coil.
primary; secondary
The quantity that gives an Ohm's Law-like relationship between voltage and current in inductors and capacitors:
reactance
Meters for use in ac circuits read the effective or____ voltages and currents.
rms
The reason rms values are used in circuit measurements is
rms values obey the same formulas for power gain or loss as in dc circuits
A measure of the emf produced in a coil due to changes in the current flowing through itself.
self-inductance
The constant of proportionality between emf and the rate of change of current in a coil is called the ___ of the coil.
self-inductance
As frequency increases, resistance
stays the same
When current in a coil increases, the energy stored in the electric field around it
stays the same
When the charge on a capacitor increases, the energy stored in the magnetic field around it
stays the same
A device for raising or lowering the voltage in an ac circuit:
transformer
