How ELECTRICITY works – working principle


hey there guys Paul here from the
engineering mindset dot com in this video we are going to be looking at how
electricity works now this is pretty essential knowledge for any engineer 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 surrounding 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 planet except that the
electrons travel in 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
number of how many electrons can be in any one orbital shell the number of
protons neutrons and electrons and 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 outermost 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 alpha 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 ie not in to us
which keeps us safe if we look inside the 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 the 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 this 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
route which electrons can flow along between the two terminals the positive
and a 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 even 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 9-volt battery can
provide 9 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 for a pipe to measure the
flow of electrons we use the unit of amp one ampere means one Coulomb per second
and one Coulomb is a group of electrons the group is incredibly large and is
approximately 6 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 electrons will naturally have some resistance the
longer the wire the greater the resistance the thick of 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 to meet electrons
flowing through it or we can also be use to create light and heat such as in an
incandescent lightbulb resistance occurs when electrons collide with atoms the
amount of collisions is different from one material to another copper has a
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 lamp to 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 an electromagnetic field by itself is just intensified by
the coil by wrapping it in a coil the magnetic field becomes so strong that
the magnetic field starts that actually affect the electrons within the wire but
we’ll look at why this occurs in the 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 we electromagnets work and it’s also the basis of how induction
motors work if you want to learn more about induction motors we’ve already
covered this in another video already to see the link on-screen now now when a
magnetic field passes across a coil of wire it will induce a voltage in that
wire caused by an induced electro-motive force which is pushing the electrons in
a certain direction if the wire is connected in a
circuit then this electro-motive 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’ll see that
we can use one call 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 buildup 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 paid back up again it’s slightly similar to a battery but
capacitors are very common and they’re in almost every single circuit board and
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
this is reversing constantly now alternating current is the most common
source of power and the plug sockets in your homes and your buildings and
schools and workplace etcetera we’ll 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 in only one direction it does not alternate 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 have 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 and another later video it’s a bit more advanced and
there’s also quite an interesting history behind why we use AC and DC and
the inventors behind that if you’ve got ten minutes I definitely recommend
having a Google or a YouTube of this too alright 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 comment section below also don’t
forget to subscribe and check out our website the engineering mindset dot com

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