ac review Wednesday test
true
in series rl circuit frequency goes up with xl, vl, zt, theta true or false
true
inductance values goes up so it is directly proportional to inductive reactance? true or false
true
is XL proportional to frequency? true or false
lenz law
when the current through a coil changes and an induced voltage is created as a result of the changing magnetic field, the direction of the induced voltage is such that it always opposes the change in current? which law is this? faradays law, lenz law, murphys law, law of returns
quadruples
when the current through an inductor doubles the stored energy doubles, quadruples, is halved, does not change
decreases
when the resistor voltage in a series rl circuit becomes greater than the inductor voltage the phase angle - increase, decrease doubled, not a factor
a
which values stays the same in parallel rl circuit when frequency increases? a. IR1 and voltages across components b. xl and IL1 c. voltages and theta d. all current branches and voltages
true
vs, vr and vl are all in phase with each other in a parallel rl circuit true or false
inductive reactance
what is the opposition to sinusoidal current in a inductor? impedance, inductive reactance, resistance, power
90 degrees
what phasor relationship between voltage and current in an purely inductive circuit? 90 degrees, 45 degrees do not know
c
what remains constant in a parallel purely inductive circuit no matter what frequency is added? a values of inductors b values of voltage c both
b
what stays the same in a purely inductive series circuit when frequency is increased or decreased? a. current and voltages across inductors or vL b vL and inductor values c power and inductor values d current and VL
increases
when current through an inductor doubles the amount of energy stored in the electromagnetic field decreases, remains constant increases or doubles
true
If inductance value goes up does current decrease? true or false
false
The overall phase angle of a parallel circuit with a resistance of 20 Ω and an inductive reactance of 25 kΩ would be nearly 90° true or false
true
The phase angle follows xl and frequency and impedance in an rl circuit? so does the phase angle increase as frequency increase true or false
loss
What is an eddy current? loss, gain, in between,
Henry
What is the basic unit of inductance? Henry, XL, Ohm, L
L
What is the symbol for inductance? Henry, XL, L, Ohm
faradays law
What law states the amount of voltage induced across a coil is directly proportional to the rate at which the current is changing that causes the phase shift? faradays law,, lenz or murphys law
impedance
What represents the total opposition to sinusoidal current? XL, impedance, XC, R
L circuit
Which circuit does the current lag the voltage by 90 degrees? L circuit, RL Circuit RLC circuit
decreases
a sinosodial voltage is applied across an inductor when the frequency is increased the current, decreases, increases, does not change, goes to zero
down
in a purely inductive series circuit if frequency is increased IT goes down or up
true
in a purely inductive series circuit if frequency is increased XL and XLT goes up true or false
90
in a rl parallel circuit the inductor lags the voltage and the resistor current by ? 45 , 90, 0, 180
true
in a series RL circuit frequency goes up and these go down It, VR true or false
voltage and current
in a series RL circuit the resistor voltage lags the souce ____________ and in phase with ______________
decreased
in a series RL circuit to make the resistor voltage greater than the inductor the frequency is increased, decreased, doubled not a factor
d
A center tap transformer has a connection at the midpoint of the secondary winding resulting in:A. two equal magnitude secondary voltages. B. two 180° out of phase secondary voltages. C. secondary voltages half that of a non-center tapped transformer with the same turns ratio. D. all of these answers are correct.
true
does Kirchhoffs voltage law apply to inductive circuits? true or false
true
does the inductance of an iron core increase if the number of turns increases - true or false
impedance increases
if frequency is raised in a parallel rl circuit what changes
true
in a parallel rl circuit frequency goes up which causes XL and zt values to increase, true or false
true
in a parallel rl circuit if frequency goes up then these go down IT, theta, IL, true or false
b
in a parallel rl circuit the current through the inductor lags the voltage and the resistor current by a 45 degrees b 90 degrees c 180 degrees d -135
true
in a parallel rl circuit vs, vr and vl are in phase at the same magnitude true or false
current and voltage
in a purely inductive circuit increase the frequency causes a decrease in ________ and an in crease in _____________ --- current and voltage, voltage and current, power and resistance
true
in a purely inductive parallel circuit if frequency increases all the currents go down including IT... true or false
true
in a purely inductive parallel circuit if frequency increases xl and xlt increases . true or false