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Why Current Decreases When Inductance or Inductive Reactance Increases?

In Inductive Circuit, Why the Circuit Current (I) Decreases, When Inductance (L) or Inductive reactance (XL) Increases?

Another question from electrical and electronics engineering interviews question and answers series.

Explain the statement that ” In an Inductive circuit, when Inductance (L) or inductive reactance (XL) increases, the Circuit Current (I) decreases“.

Why Current Decreases When Inductance or Inductive Reactance Increases

Related Question: Why Current Increases When Capacitance Increases or Capacitive Reactance Decreases?

Explanation:

We know that in DC circuits:

I = V / R,

But in case of AC circuits:

I = V / Z

Where “total resistance of AC circuits = Impedance = Z = √ (R2 + (XL – XC2)”

In case of Inductive circuit:

  • Z = √ (R2 + XL2)
  • I = V / XL or I = V / Z

It shows that in inductive circuit, Current is inversely proportional to the inductive reactance as well as inductance “L” as inductance and inductive reactances “XL” are directly proportional to each others.

Let’s check with an example to see how current reduced by inductive reactance.

When Inductance = 0.02 H

Suppose an inductive circuit where:

  • Inductance = L = 0.02 Henry
  • Voltage = V = 220 V
  • Resistance = R = 10 Ω
  • Frequency = f = 50 Hz

To find the inductive reactance;

XL = 2πfL

XL = 2 x 3.1415 x 50 x 0.02

XL = 6.28 Ω

Now circuit impedance:

Z = √ (R2 + XL2)

Z = √ (102 + 6.282)

Z = 11.8 Ω

Finally, current in inductive circuit:

I = V / Z

I = 220 V / 11.8 Ω

 I = 18.64 A 

Related Questions:

When Inductance = 0.04 H

Now we increased the Inductance (L) of inductor form 0.02 H to 0.04 H,

V = 220 V, R = 10 Ω, L = 0.04 H, f = 50 Hz.

XL = 2πfL= 2 x 3.1415 x 50 x 0.04 = 12.56 Ω

Z = √ (R2 + XL2) = √ (102 + 12.562) = 16.05 Ω

I = V / Z = 220 V / 16.05 Ω

 I = 13.70 A 

Related Questions:

Conclusion:

We can see that, When inductance (L) was 0.02 Henry, then circuit current were 18.64 A,

But when circuit inductance increased from 0.02 H to 0.04 H, then the current decreased from 18.64 A to 13.70 A.

Hence proved,

In an inductive circuit, when inductive reactance XL increases, the circuit current decreases and vice versa.

In oral or verbal,

  • Inductive reactance is a kind of resistance. When resistance increases, the circuit current decreases and vice versa.
  • Inductance is directly proportional to the inductive reactance

L ∝ XL

  • Current is inversely proportional to the inductance and inductive reactance.

I ∝ 1/L     and     I ∝ 1/XL

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3 Comments

  1. Thanks for easy explanation.

  2. PATIL VAIBHAV BHASKAR says:

    Hello,
    thank u for valuable information.
    my query is,
    why we don’t use below 50 Hz in e-machines?
    Plz give answer.

  3. Thanks sir for providing this type knowledgeable questions.
    Pls continue it sir ………….

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