Problemas circuitos AC

Prévia do material em texto

Problemas em circuitos de corrente alternada 
1- Calcule a tensão total 
 
2- An inductor rated at 4 henrys is subjected to a sinusoidal AC voltage of 24 volts RMS, at a frequency of 
60 hertz. Write the formula for calculating inductive reactance (XL), and solve for current through the 
inductor. 
3- At what frequency does a 350 mH inductor have 4.7 kΩ of reactance? Write the formula for solving this, 
in addition to calculating the frequency. 
 
4- Calculate the current 
 
5- When AC power is initially applied to an electric motor (before the motor shaft 
has an opportunity to start moving), the motor “appears” to the AC power 
source to be a large inductor: 
If the voltage of the 60 Hz AC power source is 480 volts RMS, and the motor initially draws 75 amps RMS 
when the double-pole single-throw switch closes, how much inductance (L) must the motor windings have? 
Ignore any wire resistance, and assume the motor’s only opposition to current in a locked-rotor condition is 
inductive reactance (XL). 
6- Calculate all voltage drops and current in this LC circuit at each of the given frequencies: 
Freq 
(Hz) 
50 60 70 80 90 100 
VL 
VC 
Itotal 
Also, calculate the resonant frequency of this circuit and the quality factor Q. 
Note: Q is the ratio of power stored to power dissipated in the circuit reactance and resistance, respectively: 
 Q = Pstored/Pdissipated = I2X/I2R 
 Q = X/R 
 where: X = Capacitive or Inductive reactance at resonance 
 R = Series resistance. 
7- Determine the total impedance of these networks 
 
 
8- Complete the table of values for this circuit, representing all quantities in complex-number form: 
 
 
9- Determine the input frequency necessary to give the output voltage a 
phase shift of 40o: 
 
10- Determine the necessary resistor value to give the output voltage a phase shift of 44o: 
 
Also, write an equation that solves for this resistance value (R), given all the other variables (f, L, and phase 
angle θ).