Current across resistor and inductor

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Homework Help Overview

The discussion revolves around a circuit containing a resistor and an inductor in series. The original poster seeks to understand the relationship between current, voltage, and inductive reactance, specifically questioning the applicability of Ohm's Law in this context.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants explore the definition of inductive reactance and its relationship to voltage and current. There is a discussion about the correct application of Ohm's Law in circuits with inductors, with some questioning the original poster's assumptions about current and voltage.

Discussion Status

Participants are actively clarifying terms and concepts, with some providing insights into the behavior of current in series circuits. There is an ongoing exploration of how to apply formulas correctly, particularly regarding the distinction between voltage across a resistor and an inductor.

Contextual Notes

Some participants note the importance of frequency in determining inductive reactance, which may affect the calculations being discussed. There is also a reminder about the proper terminology regarding current and voltage in circuit analysis.

verbose

Homework Statement


I have a resistor and an inductor in series. The current across each is the same, correct? I want to know if I can use Ohm's Law to solve for current across the inductor if I know the Voltage and inductive reactance. Basically, does I = V/X_{L} ?


Homework Equations



V = IR
I = V/R

does I = V/ X_{L} ?

The Attempt at a Solution

 
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??What do you mean by X_{L}? I can guess that V is the voltage drop, I the current and R the resistance. Is X_{L} the inductance? If so then, no, the voltage drop over an inductance is NOT given by the same equation as for a resistance. Surely you have that formula in your text?
 
X_{l}

by this i mean inductive reactance...sorry, it's tex syntax for X with L as a subscript. i have the habit of writing all my mathy stuff in latex syntax
 
verbose said:
by this i mean inductive reactance...sorry, it's tex syntax for X with L as a subscript. i have the habit of writing all my mathy stuff in latex syntax
Yes, [tex]I = \frac{V_L}{X_L}[/tex]
Notice that [tex]X_L[/tex] is dependent of the frequency of [tex]V_L[/tex]
 
verbose said:

Homework Statement


I have a resistor and an inductor in series. The current across each is the same, correct? I want to know if I can use Ohm's Law to solve for current across the inductor if I know the Voltage and inductive reactance. Basically, does I = V/X_{L} ?


Homework Equations



V = IR
I = V/R

does I = V/ X_{L} ?

The Attempt at a Solution


Forget the problem for a minute, first let's clear up that current isn't across anything. Current flows through and voltage is established across. Like fingers on a chalk board.:cry:
 
If those 2 elements are in series (the resistor and inductor) and connected to a voltage source, the current through all elements will be given by:

I = VS / (R + XL)


If the voltage you are talking about is the voltage across the inductor, then yes, the current through all elements will given by:

I = VL / XL
 

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