Inductive Circuit and Frequency

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Homework Help Overview

The problem involves a series circuit containing a resistor and a capacitor connected to a variable frequency supply, with voltmeters measuring the voltage across the inductor and the resistor. The context centers around understanding how the readings on these voltmeters change as the frequency of the supply is increased.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between frequency, inductive reactance, and voltage across the components. Some express confusion regarding the terminology and concepts, such as inductive reactance and its implications on voltage readings. Questions arise about the correct configuration of the circuit and whether it includes all three components: resistor, capacitor, and inductor.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem setup. Some have provided insights into reactance and its effect on voltage, while others are questioning the original poster's understanding and the clarity of the problem statement. There is no explicit consensus on the correct interpretation yet.

Contextual Notes

Participants note potential confusion in the problem statement regarding the components involved, specifically whether it is a series R + C or R + L circuit. This ambiguity may affect the understanding of the voltage behavior in the circuit.

ah4p
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Homework Statement



A resistor and a capacitor are connected in series to a variable frequency supply. A voltmerter is connected across the inductor and another across the resistor. The supply voltage is kept constant as frequency of supply is increased.
State and explain the changes in the readings on voltmeters across the inductor and across the resistor

Homework Equations



current is inversely proportional to frequency in an inductive circuit

V=IR

The Attempt at a Solution



I thought across the inductor V decreases since I will decrease as a result of frequency increasing

therefore to keep total V constant the V across the resistor will increase

4. Actual ANSWER

the answer however is V across resistor increases because Inductive reactance increases & Current decreases

so V across inductor decreases

I've never been taught what inductive reactance means?

can anyone explain why this is the answer
thank you very much in advance :)
my prelim is on MOnday :( and I'm so failing
 
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First phrase says R series C ... the rest talks about L ... are there all 3, or just L?
reactance "X" is a "generalized resistance" ... how much (volt-wise) does the device "react" to conducting AC current?
V(AC) = I X
for a Resistor, XR = R , no matter what the frequency is.
for a capacitor, XC = 1/ωC ... since small amount of charge collects in short time, at high frequency.
for an inductor, XL = ωL ... since the current changes more rapidly at high frequency.


You have R series L, so they have the same current;
what happens to the Resistor's voltage, if the current is limited by the inductor (at high frequency)?
 
lightgrav said:
First phrase says R series C ... the rest talks about L ... are there all 3, or just L?
reactance "X" is a "generalized resistance" ... how much (volt-wise) does the device "react" to conducting AC current?
V(AC) = I X
for a Resistor, XR = R , no matter what the frequency is.
for a capacitor, XC = 1/ωC ... since small amount of charge collects in short time, at high frequency.
for an inductor, XL = ωL ... since the current changes more rapidly at high frequency.You have R series L, so they have the same current;
what happens to the Resistor's voltage, if the current is limited by the inductor (at high frequency)?

oh it would increase since the electrons require more energy to move through it??

thanks for replying
 
ah4p said:
4. Actual ANSWER

the answer however is V across resistor increases because Inductive reactance increases & Current decreases

so V across inductor decreases
Unfortunately, this cannot be the correct answer. It is contradictory in itself. Please check whether you have transcribed this incorrectly.

You haven't answered lightgrav's question: does this problem involve a series R + C or a series R + L. You have mentioned both, probably a careless mistake due to haste, or you may be mixing up two separate questions.
 
You did not describe the position of the inductor in the circuit.
 

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