Voltage drop across paralell resistor and capacitor

AI Thread Summary
To find the voltage drop across a parallel resistor and capacitor, calculate the complex impedance using the formula for resistors in parallel. The complex impedance of the capacitor is given by Z_c = 1/(i*omega*C). Apply Ohm's law to determine the complex voltage across the net impedance when driven by the specified current of 100 mA. The magnitude of the resulting complex voltage can be found by taking the square root of the product of the complex quantity and its conjugate. Understanding these calculations will clarify the application of complex impedance in this context.
teroenza
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Homework Statement


Find the voltage drop across a resistor and capacitor in parallel. I am trying to understand how to deal with this using complex numbers. I may have a completely wrong notion of complex impedance. I thought I could treat the complex impedance like resistance, then take the modulus or real part (I believe I know the math, but not which to apply).


I= 100 milli Amps
R= 1000 ohms
C= 0.001Farads
freq.= 60Hz=377rad/s



Homework Equations


Z_c=1/(i*omega*C)

R_eq= (R*Z_C)/(R+Z_C)


The Attempt at a Solution


Do I apply the standard resistors in parallel formula then take the real part of the modulus? Or do I have a completely wrong conception on complex impedance.
 
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teroenza said:

Homework Statement


Find the voltage drop across a resistor and capacitor in parallel. I am trying to understand how to deal with this using complex numbers. I may have a completely wrong notion of complex impedance. I thought I could treat the complex impedance like resistance, then take the modulus or real part (I believe I know the math, but not which to apply).


I= 100 milli Amps
R= 1000 ohms
C= 0.001Farads
freq.= 60Hz=377rad/s



Homework Equations


Z_c=1/(i*omega*C)

R_eq= (R*Z_C)/(R+Z_C)


The Attempt at a Solution


Do I apply the standard resistors in parallel formula then take the real part of the modulus? Or do I have a completely wrong conception on complex impedance.

Calculate the complex impedance as you've suggested using the 'usual' formula for resistors in parallel. Apply Ohm's law to find the (complex) voltage that will appear across the net impedance when driven by the 100mA current. The magnitude of that complex quantity should be what you're looking for.
 
To be sure I fully understand, by magnitude you mean take the square root of (my complex quantity * its complex conjugate) ?
 
teroenza said:
To be sure I fully understand, by magnitude you mean take the square root of (my complex quantity * its complex conjugate) ?

Yes.
 
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