How to find supply frequency of an AC circuit

  • #1

Homework Statement


[/B]
Parallel circuit consists of 100ohm resistor with 0.4A current, a 0.47uf capacitor with 0.177A current. Both connected across an AC supply, determine


Homework Equations


[/B]
The supply voltage
The supply frequency
Current drawn from supply
Power factor of the circuit
The Apparent power

The Attempt at a Solution


[/B]
The supply voltage is 40V.
Supply frequency is where im stuck at the minute. I have VL=VC=XC

So VC=1/(2PiFC)
Substitute F for VC and I get VC=1/(2PiC*VC)
F= 1/(2Pi *0.47x10-6*40V)
Doing that equation I get 8465.69Hz which is crazy?

Thanks in advance Alan
 
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Answers and Replies

  • #2
BvU
Science Advisor
Homework Helper
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Hello Alan, welcome to PF :)

Do the relevant equations look like equations to you ?

I take it the 40 V follows from I = V/R, so that qualifies as an equation and you have attempted a solution (and it's OK)

Perhaps the 0.177 and the 0.47 uF plus the 40 V can lead you to a frequency -- if you have a decent equation at hand, that is. Any idea ?


PS Check out the guidelines
 
  • #3
gneill
Mentor
20,945
2,886

Homework Statement



Parallel circuit consists of 100ohm resistor with 0.4A current, a 0.47uf capacitor with 0.177A current. Both connected across an AC supply, determine[/B]


Homework Equations



The supply voltage
The supply frequency
Current drawn from supply
Power factor of the circuit
The Apparent power[/B]

The Attempt at a Solution



The supply voltage is 40V.
Supply frequency is where im stuck at the minute. I have VL=VC=XC

So VC=1/(2PiFC)
Substitute F for VC and I get VC=1/(2PiC*VC)
F= 1/(2Pi *0.47x10-6*40V)
Doing that equation I get 8465.69Hz which is crazy?
[/B]
Thanks in advance Alan
Hello Alan,

Welcome to Physics Forums.

Voltage and reactance are not the same thing (one has units of Volts and the other Ohms). You have the potential across the capacitor (40 V) and the current though it, so you can determine the reactance...
 
  • #4
This is where Im at now, Xc=V/I wich is 40V/0.177A=225.99

F= 1/(2Pi * 0.47x10-6 * 225.99)= 1498.41Hz
 
  • #5
BvU
Science Advisor
Homework Helper
15,029
4,079
Well done
 
  • #7
BvU
Science Advisor
Homework Helper
15,029
4,079
How to calculate frequency of AC signal?
Hello Sanat, :welcome:
Please start a new thread for this question and use the homework template.
 

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