Hey there, guys, Paul here from theengineeringmindset.com. In this video, we are going to be looking at how electricity works. Now, this is pretty essential knowledge for any engineering, so we'll
run through the basic parts of what you need to know. So let's start at the very basics and for that, we need to
take a look at the atom. Everything, including
you, is made from atoms. All the materials we
use are made from atoms. The materials are just different because the construction of their atoms are slightly different. The atoms are made from three particles, two of which are found inside the nucleus and the third particle sits outside this. At the center of the
atom, we have the nucleus. Inside the nucleus, we have the neutrons, which have no charge, and
we also have the protons, which are positively charged. The neutrons and the
protons are much heavier than the electrons so these
will stay within the nucleus. Surround the nucleus are different
layers of orbital shells. These are like flight
paths for the electrons. The electrons flow
along these flight paths much like a satellite orbits our plant, except that the electrons travel at almost the speed of light. The electrons are negatively charged and they are attracted
to the positive charge of the protons. The electrons orbit around the nucleus in these orbital shells
and there are a set numbers of how many electrons can
be in any one orbital shell. The number of protons, neutrons,
and electrons an atom has tells us which material it is. Atoms hold on to their
electrons very tightly, but some materials will
hold on to them more tightly than others. The outer-most shell is
known as the valence shell, and in this shell, some materials have
loosely bound electrons which can flow to other atoms. Atoms which can pass electrons
are called conductors and most metals are conductors. On the other hand, atoms which
do not have free electrons and so they can't pass
electrons between other atoms are known as insulators. And these are things
like glass and rubber. Now, we can combine these materials to safely use electricity by having the conductor in the center, which allows electrons to move, but surround this with an insulator to restrict where they can flow to, i.e., not lead to us, which keeps us safe. If we look inside a slice of copper cable at the free electrons
surrounding the nucleus of the copper atom, you'll
see that the free electrons are able to move to other atoms, but this happens randomly
in any direction. If we then connect this
slice of copper cable to a closed circuit with a power source, such as a battery, then the
voltage will force the electrons to move and these will then all flow in the same direction to try and get back to the other terminal of the battery. When I say circuit,
this just means the root which electrons could flow along between the two terminals,
the positive and the negative, of a power source. So we can add things into their path, like light bulbs, and this
means that the electrons will have to pass through
this in order to get to the other terminal. And so we can use this to
create things such as light. The circuit can either be open or closed. In a closed circuit,
that means the electrons can flow around. And in an open circuit, this
means that the electrons are not able to flow. Voltage is a pushing force of
electrons within a circuit. It's like pressure in a water pipe. The more pressure you have,
the more water can flow. The more voltage you have,
the more electrons can flow. But what does a volt mean? Well, a volt is a joule per coulomb. And a joule is a measurement
of energy or work and a coulomb is a group
of flowing electrons. We'll have a look at what a coulomb is in just a second though. So a nine volt battery
can provide nine joules of energy in the form of work or heat per group of electrons that flow from one side of the battery to the other. In this case, the current of electrons flow from one side of the battery through the LED light
bulb, which produces light, and then the electrons
flow to the other side of the battery, therefore,
nine joules of light and heat is produced by the light bulb. Current is the flow of electrons. When a circuit is closed, it means electrons can flow,
and when the circuit is open, no electrons will flow. We can measure the flow of electrons just like you can measure the
flow of water through a pipe. To measure the flow of electrons, we use the unit of amp. One amp means one coulomb per second and one coulomb is a group of electrons. The group is incredibly
large and is approximately six billion, 242 million,
billion electrons, and that has to pass in one second for it to equal one amp. That's why electrons are grouped together and just called amps, to
make it easier for engineers. Resistance is a restriction
to the flow of electrons in a circuit. The wire which carries the electrons will naturally have some resistance. The longer the wire, the
greater the resistance. The thicker the wire,
the lower the resistance. Resistance to the flow of electrons is different for each material. And the temperature of the material can also change resistance
to the flow of electrons. Electrical circuits use
specially designed components known as resistors to
purposely restrict the flow of electrons. This is either to protect other components from too many electrons flowing through it or it can also be used
to create light and heat, such as in an incandescent light bulb. Resistance occurs when
electrons collide with atoms. The amount of collisions is
different from one material to another. Copper has very low collision rate, but other materials such as iron will have much more collisions. When collisions occur,
the atoms generate heat and at a certain temperature, the material will then
start to produce light as well as heat, which is how
the incandescent lamps work. When a wire is wrapped in a coil, it will generate a magnetic field as the current passes through it. The cable will naturally
create electromagnetic field by itself. It's just intensified by the coil. By wrapping it in a coil, the magnetic field becomes so strong that the magnetic field starts to actually affect the electrons within the wire. But we'll look at why this occurs in a future, more advanced video. We can increase the strength
of the magnetic field simply by wrapping the
coils around an iron core. We can also increase the number
of turns within the coils and also we can increase
the amount of current passing through the circuit. And this is how electromagnets work and it's also the base of
how induction motors work. If you want to learn more
about induction motors, we've already covered this
in another video already. Just see the link on the screen now. And when a magnetic field
passes across the coil of wire, it will induce a voltage in that wire caused by an induced electromotive force, which is pushing electrons
in a certain direction. If the wire is connected in a circuit, then this electromotive force
will cause a current to flow. This is the basis of
how AC generators work and the electricity at your
wall sockets within your home is produced in a very similar way. Transformer, now, we can
combine all of the aspects together that we've just covered and when we do so, we will
see that we can use one coil to generate electricity and then we can place two other coils in very close proximity to
each other but not touching, and this will create a transformer. The transformer will induce a voltage from the first of the primary coil over into the secondary coil. And this will force electrons to flow if the coil in the secondary side has a closed circuit. Now what's important about the transformer is that we can increase
or decrease the voltage between the primary
and the secondary coils simply by changing the amount
of coils on either side. Again, this is a subject all by itself so we'll cover this in a
more advanced video later on. Now, something else which I
just want to briefly mention is the capacitor. So, a capacitor forces
positive and negative charges to separate across two plates when it is connected to a power supply. This causes a build-up
or store of electrons within an electric field. When the power supply
is cut or interrupted, these charges will then be released, flow up, and meet again. This provides a power source
but only for a few seconds until the charges have
paired back up again. It's slightly similar to a battery, but capacitors are very common and they're in almost
every single circuit board. We'll cover this obviously in more detail in a future video. Just be aware of these. So the last part I want
to cover in this video is that there are two types
of current electricity. That being alternating current, or AC, and then direct current, or DC. Alternating current simply means that the current flows
backwards and forwards in a circuit as the terminals
are constantly reversed. This is a bit like the tide of the sea. It goes in and out, in
and out, in and out. So there is reversing constantly. Now, alternating current
is the most common source of power and the plug
sockets in your homes, in your buildings, in schools,
and work places, et cetera, these will all be providing
alternating current, AC. Now, on the other hand, we've
got direct current, or DC, and that simply means
that the current flows directly in only one direction. It is not alternating. This is what's provided from batteries and almost all your handheld devices are from this, as well. So we can convert AC to DC and vice versa using power electronics. And this is how we charge and power, you know, small devices, and it's also how solar panels can be used to power our homes. Because solar panels produce DC power and our homes need AC power. So we have to convert
this for it to be usable. So both AC and DC have
pros and cons to it, but, you know, for sure we'll look at this in another later video. It's a bit more advanced. And there's also quite
an interesting history behind why we use AC, DC, and
the inventors behind that. If you've got 10 minutes,
I definitely recommend having a Google or a YouTube of this, too. All right, that's it for this video. Thank you very much for watching. I hope you enjoyed this and it helped you. If you have any questions, please leave me in the
comments section below. Also don't forget to subscribe
and check out our website, theengineeringmindset.com.
It's been so long since I learned about electricity I forgot this.