# How to find supply frequency of an AC circuit

• Alan McMaster
In summary, the supply frequency of an AC circuit refers to the number of complete cycles of alternating current that occur per second and is typically 50 or 60 Hz. It can be calculated by dividing the number of cycles by the time taken and is primarily determined by the power grid and generator. Factors such as load, voltage, and frequency changes can also affect the supply frequency. Specialized equipment can be used to change the frequency, but a mismatch between the supply frequency and equipment's required frequency can cause damage or affect performance. It is important to always ensure a match between the two.
Alan McMaster

## 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 I am 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?

Last edited by a moderator:
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

Alan McMaster said:

## 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 I am 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]
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...

This is where I am at now, Xc=V/I which is 40V/0.177A=225.99

F= 1/(2Pi * 0.47x10-6 * 225.99)= 1498.41Hz

Well done

How to calculate frequency of AC signal?

Sanat Mishra said:
How to calculate frequency of AC signal?
Hello Sanat,
Please start a new thread for this question and use the homework template.

## 1. What is the supply frequency of an AC circuit?

The supply frequency of an AC circuit refers to the number of complete cycles of alternating current that occur per second. It is measured in Hertz (Hz) and is typically 50 or 60 Hz for most household and industrial circuits.

## 2. How do I calculate the supply frequency of an AC circuit?

The supply frequency can be calculated by dividing the number of cycles of alternating current by the time taken for those cycles to occur. This can be measured using an oscilloscope or a frequency meter.

## 3. What factors affect the supply frequency of an AC circuit?

The supply frequency of an AC circuit is primarily determined by the power grid and the generator used to produce the electricity. However, factors such as load on the circuit, changes in voltage, and changes in frequency can also affect the supply frequency.

## 4. Can I change the supply frequency of an AC circuit?

In most cases, the supply frequency of an AC circuit cannot be changed as it is determined by the power grid. However, some specialized equipment, such as frequency converters, can be used to change the frequency for specific applications.

## 5. What are the implications of a mismatch between the supply frequency and the equipment's required frequency?

If there is a mismatch between the supply frequency and the equipment's required frequency, it can cause damage to the equipment or affect its performance. It is important to always ensure that the supply frequency matches the frequency requirements of the equipment being used.

• Introductory Physics Homework Help
Replies
9
Views
1K
• Introductory Physics Homework Help
Replies
9
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
892
• Introductory Physics Homework Help
Replies
10
Views
2K
• Introductory Physics Homework Help
Replies
5
Views
2K
• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
7
Views
2K
• Electrical Engineering
Replies
17
Views
2K
• Introductory Physics Homework Help
Replies
4
Views
2K
• Introductory Physics Homework Help
Replies
14
Views
2K