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Inductors Explained - The basics how inductors work working principle - YouTube
Channel: The Engineering Mindset
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Hey there guys.
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Paul here from TheEngineeringMindset.com.
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In this video, we're going
to be looking at inductors
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to learn how they work, where we use them,
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and why they're important.
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Remember, electricity is
dangerous and can be fatal.
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You should be qualified and competent
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to carry out any electrical work.
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So, what is an inductor?
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An inductor is a component
in an electrical circuit
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which stores energy in its magnetic field.
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It can release this
energy almost instantly,
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and we'll see how it does
that later on in this video.
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Being able to store and
quickly release energy
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is a very important feature,
and that's why we're going
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to use these in all sorts of circuits.
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Now, in our previous video,
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we looked at how capacitors work.
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Do check that out if you haven't
already, link's down below.
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So, how does an inductor work?
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I want you to first
think about water flowing
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through some pipes.
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There is a pump which pushes this water,
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and the pump is equivalent to
our battery in the circuit.
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The pipe will split into two branches,
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and the pipes are equivalent to our wires.
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One branch has a pipe
with a reducer in it,
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and that reduction
makes it a little harder
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for water to flow through it.
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So, the reducer is equivalent
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to resistance in our electrical circuit.
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The other branch has a
water wheel built into it.
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The water wheel can rotate,
and the water flowing
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through it will cause it to rotate.
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The wheel is very heavy, though,
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so it takes some time
to get it up to speed,
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and the water has to
keep pushing against this
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to get it to move.
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This water wheel is going to
be equivalent to our inductor.
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When we first start the pump,
the water is going to flow
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and it wants to get back to the pump,
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as this is a closed loop.
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This is just like when
electrons leave the battery,
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they flow and try and get back
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to the other side of the battery.
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By the way, in these
animations, I use electron flow,
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which is from negative to positive,
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but you might be used to
seeing conventional flow,
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which is from positive to negative.
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Just be aware of the two
and which one we're using.
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So, as the water flows,
it reaches the branches
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and it has to now decide
which path to take.
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The water pushes against the wheel,
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but the wheel is going to
take some time to get moving,
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and so it's adding a lot
of resistance to the pipe,
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making it too difficult for the water
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to flow through this path.
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Therefore, the water will
instead take the path
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of the reducer because it can
flow straight through this
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and get back to the pump much easier.
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As the water keeps pushing,
the wheel will begin to turn
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faster and faster until it
reaches its maximum speed.
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Now the wheel doesn't provide
almost any resistance,
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so the water can flow
through this path much easier
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than the path with the reducer in it.
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The water will pretty much
stop flying through the reducer
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and it will all now flow
through the water wheel.
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When we turn off the pump,
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no more water will enter the system,
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but the water wheel is going so fast,
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it can't just stop, it has inertia.
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As it keeps rotating, it
will now push the water
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and acts like a pump.
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The water will flow around
the loop back on itself
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until the resistance in the pipes
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and the reducer slows
the water down enough
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that the wheel stops spinning.
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We can, therefore, turn
the pump on and off,
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and the water wheel will
keep the water moving
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for a short duration
during these interruptions.
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We get a very similar scenario
when we connect an inductor
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in parallel with a resistive
load, such as a lamp.
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This is the same circuit as we just saw,
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but I've just wired it more neatly.
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When we power the circuit, the
electrons are going to first
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flow through the lamp and power it.
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Very little current will
flow through the inductor
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because of its resistance,
at first, is too large.
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The resistance will reduce and
allow more current to flow.
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Eventually, the inductor
provides nearly no resistance,
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so the electrons will prefer
to take this path back
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to the power source rather
than through the lamp,
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so the lamp will turn off.
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When we disconnect the power supply,
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the inductor is going to
continue pushing electrons
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around in a loop and through the lamp
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until the resistance
dissipates the energy.
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So, what's happening in the inductor
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for it to act like this?
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Well, when we pass electrical
current through a wire,
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the wire will generate a
magnetic field around it.
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We can actually see this magnetic field
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by placing compasses around the wire.
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When we pass a current through the wire,
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the compasses will move and
align with the magnetic field.
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When we reverse the
direction of the current,
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the magnetic field reverses,
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and so the compasses will
also reverse direction
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to align with this.
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The more current we pass through the wire,
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the larger the magnetic field becomes.
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When we wrap the wire into a coil,
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each wire again produces a magnetic field
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but now it will all merge together
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and form one large, more
powerful magnetic field.
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We can see the magnetic field of a magnet
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just by sprinkling some iron
filings over the magnet,
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which will reveal the magnetic flux lines.
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When the electricity supply is off,
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no magnetic field exists,
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but when we connect the power supply,
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current will begin to
flow through the coil,
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so our magnetic field will begin to form
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and increase in size, up to its maximum.
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The magnetic field is storing energy.
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When the power is cut, the
magnetic field will begin
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to collapse, and so the
magnetic field will be converted
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into electrical energy and this
pushes the electrons along.
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In reality, it's going to
happen incredibly fast.
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I've just slowed these animations down
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to make it easier to see and understand.
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So, why does it do this?
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Well, inductors don't
like changing current;
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they want everything to remain the same.
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When the current increases,
they try to stop it
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with an opposing force.
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When the current decreases,
they try to stop it
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by pushing electrons out to
try and keep it the way it was.
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So, when the circuit goes from off to on,
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there will be a change in
current, it has increased.
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The inductor is going to try to stop this,
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and so it creates an opposing force
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and there's a back EMF,
or electromotive force.
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This back EMF opposes the
force which created it.
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In this case, that's the current flowing
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through the inductor from the battery.
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Some current is still going
to flow through, though,
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and as it does, it
generates a magnetic field,
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which will gradually increase.
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As it increases, more and
more current will flow
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through the inductor and the back EMF
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will eventually fade away.
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The magnetic field will reach its maximum
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and the current stabilizes.
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The inductor no longer
resists the flow of current
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and acts like a normal piece of wire.
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This creates a very easy
path for the electrons
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to flow back to the battery,
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much easier than flowing through the lamp.
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So, the electrons will
flow through the inductor
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and the lamp will no longer shine.
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When we cut the power,
the inductor realizes
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that there has been a
reduction in current.
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It doesn't like this and
tries to keep it constant,
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so it's going to push electrons
out and try to stabilize it.
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This will power the light up.
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Remember, the magnetic
field has stored energy
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from the electrons flowing through it,
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and it will convert this
back into electrical energy
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to try and stabilize the current flow.
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But the magnetic field will only exist
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when the current passes through the wire,
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and so, as the current
decreases from the resistance
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of the circuit, the
magnetic field collapses
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until it no longer provides any power.
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If we connected a resistor and an inductor
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in separate circuits to an oscilloscope,
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then we can visually see the effects.
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When no current flows,
the line is constant
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and flat at zero, but when we pass current
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through the resistor, we
get an instant vertical plot
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straight up, and then
it flat-line continues
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at the certain value.
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But when we connect an inductor
and pass current through it,
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it will not instantly rise up,
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it will gradually increase
and form a curved profile,
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eventually continuing at a flat rate.
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When we stop the current
flowing through the resistor,
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it, again, instantly drops
and we get this sudden
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vertical line back down to zero,
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but when we stop the current
through the inductor,
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the current continues and we get another
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curved profile down to zero.
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This shows us how the inductor
resist the initial increase
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and also tries to prevent the decrease.
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By the way, we've covered
electrical current in detail
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in a previous video.
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Do check that out, link's down below.
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What do inductors look like?
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Inductors in circuit boards
will look something like this,
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basically, just some copper
wire wrapped around a cylinder
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or a ring.
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We do get some other designs,
which have some casing over.
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This casing is usually to
shield the magnetic field
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and prevent this from interfering
with other components.
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We will see inductors represented
on engineering drawings
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with symbols like these.
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Something to remember is that everything
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with a coiled wire will
act as an inductor.
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That includes motors,
transformers, and relays.
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So, what do we use inductors for?
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We use them in boost converters
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to increase the DC output voltage
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while decreasing the current.
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We can use them to choke an AC supplier
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and only allow DC to pass.
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We can use them to filter
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and separate different frequencies,
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and obviously, we also use them
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for transformers, motors, and relays.
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How do we measure inductance?
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We measure the inductance
of an inductor in the unit
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of Henry with a capital H.
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The larger the number,
the higher the inductance.
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The higher the inductance,
the more energy we can store
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and provide.
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It will also take longer for
the magnetic field to build
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and the back EMF will
take longer to overcome.
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You can't measure inductance
with a standard multimeter,
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although you can get some models
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with this function built-in,
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but it won't give you the
most accurate results.
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That might be okay for you,
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it depends on what you're using it for.
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To measure inductance accurately,
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we need to use an RLC meter.
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We simply connect the inductor to the unit
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and it will run a quick
test to measure the values.
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Okay, guys, that's it for this video,
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but to continue your learning,
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then check out one of
the videos on-screen now
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and I'll catch you there
for the next lesson.
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Don't forget to follow us on
Facebook, Twitter, Instagram,
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as well as TheEngineeringMindset.com.
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