# If an inductor requires a changing current to produce a voltage drop across itself

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Then is there any purpose to an inductor with constant current going through it? Is AC usually used with inductors since its always changing.

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47 minutes ago, Hulk said:

Then is there any purpose to an inductor with constant current going through it? Is AC usually used with inductors since its always changing.

Can't think of any uses?

How about battery powered door chimes?

Magnetic braking?

Magnetic lock?

In fact anwhere that you want something mechanical held in or out of position.

Any current going through an inductor generates a magnetic field.
A constant direct current generates a constant magnetic field.

So no, a/c is not 'normally used'. Further a/c can be steady or varying itself.

But we can use that constant magnetic field for instance in focusing electron beams or anywhere that we require a magnetic field such as magnetic grapples, magnetic force between the poles of a D'Arsnoval meter and many many more.

A final class of uses occurs in electronics where chokes (large value inductors) are used for smoothing purposes.

What is you interest in the subject?

Edited by studiot
spelling

Does this count?

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3 hours ago, studiot said:

What is you interest in the subject?

I am not sure, sorry!

Here is another question if you may please help with, if an inductor stores energy in a magnetic field, what type of energy is it? Capacitor is easy cause it stores energy in an electric field and more or less it is simply more electrons on one side then the other which means its potential energy. What about an inductor, I don't get how energy is stored in a magnetic field...

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The energy (per unit volume) of an electric field is

$\frac{1}{2}DE$ Joules/m3

Where E is the electric field and D the electric displacement.

The energy (per unit volume) of a magnetic field is

$\frac{1}{2}BH$ Joules/m3

Where B and H are magnetic field vectors

The energy (per unit volume) of an elastic field is

$\frac{1}{2}stress\;x\;strain$ Joules/m3

The energy (per unit volume) of an gravitational field is

$\frac{1}{2}{D_0}g$ Joules/m3

Where D0 is the gravitational flux and g the local gravitational constant

Can you see a pattern here?

Edited by studiot
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On 9/16/2018 at 6:40 AM, studiot said:

The energy (per unit volume) of an electric field is

12DE Joules/m3

Where E is the electric field and D the electric displacement.

The energy (per unit volume) of a magnetic field is

12BH Joules/m3

Where B and H are magnetic field vectors

When an inductor discharges its magnetic field does it produce a current?

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1 hour ago, Hulk said:

When an inductor discharges its magnetic field does it produce a current?

If a suitable conductor intersects that collapsing field yes.

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