What is the approach to solving this AC circuit voltage problem using phasors?

In summary, the problem is given in the attachment. The student has basic knowledge of ac circuits and phasor diagrams, but is confused about how to proceed in this question. They want to grasp the concept of the question.
  • #1
aryan pandey
9
0

Homework Statement


the problem is given in the attachment

Homework Equations


basic knowledge of ac circuits and phasor diagrams

The Attempt at a Solution


for point A , i calculated the potential easily. and for point B , i calculated the potential using phasor relationship .. now after doing VA - VB, i got the relation that its modulus will first decrease and then eventually increase
but in the answer given is that modulus of VA - VB will remain unchanged.
IMG_9407.JPG
 
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  • #2
You'll have to show the details of how you got your relation. Can't fix what we can't see :wink:
 
  • #3
truely speaking , i am confused how to proceed this question and hence not able to provide my approach .
through this question i want to grasp the concept of the question.
 
  • #4
aryan pandey said:
truely speaking , i am confused how to proceed this question and hence not able to provide my approach .
through this question i want to grasp the concept of the question.
Well, could you post the phasor diagram that you've drawn?
What can you say about the locus of VB from the fact that R1 and R2 are equal?
 
  • #5
aryan pandey said:
truely speaking , i am confused how to proceed this question and hence not able to provide my approach .
through this question i want to grasp the concept of the question.
You should think about the extreme cases. What hapen when R=0 and when R tends to infinity maybe that helps as a start. Anyway you have to get an equation for Vab in function of the variable recistance.
 
  • #6
aryan pandey said:
truely speaking , i am confused how to proceed this question and hence not able to provide my approach .
through this question i want to grasp the concept of the question.
Start by writing expressions for the potentials at points A and B. You referred to phasors, and that's a great idea. You can work graphically or algebraically (complex value phasor representation). The complex value method employs complex impedances.

Hint: Since the AC frequency is not changing the reactance of the capacitor will not change: It will be a constant. So just assign an arbitrary name to the capacitor impedance, say -jZ. (You do recall that in terms of phasors the impedance of a capacitor has a negative imaginary value, right?)
 

1. How do I calculate the voltage in an AC circuit?

The voltage in an AC circuit can be calculated using the formula V=IR, where V is the voltage, I is the current, and R is the resistance. However, in AC circuits, the voltage is constantly changing, so you will need to use the equation V=IRcos(ωt), where ω is the angular frequency of the AC source and t is the time.

2. What is the difference between AC and DC voltage?

The main difference between AC (alternating current) and DC (direct current) voltage is the direction of the flow of electricity. In an AC circuit, the direction of the current changes constantly, while in a DC circuit, the current flows in one direction. AC voltage is also typically higher than DC voltage, and is used for long-distance power transmission.

3. How does the voltage affect the overall performance of an AC circuit?

Voltage is a crucial factor in determining the performance of an AC circuit. Higher voltage can lead to an increase in current flow, which can result in more power being delivered to the circuit. However, if the voltage is too high, it can cause damage to the circuit components. On the other hand, if the voltage is too low, the circuit may not function properly.

4. What is the difference between peak and RMS voltage in an AC circuit?

Peak voltage is the maximum voltage that occurs in an AC circuit, while RMS (root mean square) voltage is the effective voltage that produces the same amount of power as the peak voltage in a DC circuit. In other words, RMS voltage takes into account the constant changing of voltage in AC circuits, and is a more accurate measure of the voltage level.

5. How does the reactance in an AC circuit affect the voltage?

Reactance is the opposition to the flow of electricity in an AC circuit, caused by inductance or capacitance. In an AC circuit, reactance can affect the voltage by creating a phase difference between the voltage and current, which can result in a decrease or increase in the overall voltage. This is why reactance is an important factor to consider when calculating the voltage in an AC circuit.

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