– Hey there guys, Paul here

from theengineeringmindset.com In this video we’re going

to be looking at Ohm’s Law to understand how it works

as well as how to use it. There are also two problems

at the end of this video for you to test your knowledge

and see if you can solve. So, what is Ohm’s Law? Ohm’s Law is a relationship between voltage, current, and resistance and how they relate to each other. Ohm’s Law was developed

by German physicist, named Georg Ohm, who undertook many experiments

to develop his theory, including measuring current by touching the live electrical circuits to see how much it hurt. As you might imagine, the higher the current, the more it hurt. Now, there are three formulas

we need to use for Ohm’s Law, but we don’t actually

need to remember these and I’ll show you a super

easy tip in just a moment. So, the three formulas

we use for Ohm’s Law are, voltage equals current

multiplied by resistance, current equals voltage

divided by resistance, and resistance equals

voltage divided by current. If that seems like a lot to

remember, then don’t worry, because we don’t need to remember them. All we need to remember is Ohm’s triangle, which looks like this. So, you just need to remember

these three letters in order. V-I-R. Then we just write

those down in a triangle with V at the top and we draw a line to

separate the letters. In fact, you don’t even

need to remember those, because I’ve made a free PDF guide for you with some worked examples

which you can keep on your PC or your mobile and

access wherever you need. Links for that can be found in the video description down below. Now, all we do when we

need to use a formula is cover up the letter we need. So, if we want to find the voltage, then we write V=and then we cover up

the V in the triangle. That leaves us with I and R, so we write I multiplied by R, which means voltage equals

current multiplied by resistance. You can write a little

multiplication symbol in the triangle between the two letters if it helps you. Now, I know what you’re thinking. Why is current represented with a letter I and not a C for current? Or even a letter A for the unit of Ampere. Well the unit of current

is the Ampere or the Amp and this is named after Andre

Ampere, a French physicist. A couple of hundred years ago, he undertook lots of experiments, many involved varying the

amount of electrical current. So, he called this intensite du courant or the intensity of current. So, when he published his

work, they took the letter I and it became standard until this day. Now, you might also come across

formulas where the letter E is used instead of V. The letter E stands for

EMF, or Electromotive Force, but don’t worry about that, just stick to using V

and substitute V for E if you see it used in

Ohm’s Law’s questions. Anyway, so by covering V, we get voltage equals current

multiplied by resistance. If we want to find current then we write down I=and then we cover up the

letter I in the triangle. That gives us V and R, so as V is above the R like a fraction we can write V divided by R. Therefore, current is equal to voltage divided by resistance. If we want to find resistance, then we write down R=and then we cover up R in the triangle. That leaves us with V and I. So, we write V divided by I, which gives us resistance

equals the voltage divided by current. Let’s look at some examples

for how to use these formulas. First, let’s see how we find voltage and how it relates to the other parts. Let’s say we have a

simple electrical circuit with a battery and a resistor. We don’t know what the voltage

of the battery is though. The resistor is 3 Ohms and when we connect a multi

meter into the circuit, we see that we get a reading

of two Amps of current. We want to find the voltage. So, using Ohm’s triangle,

we can cover up the V and that gives us V

equals I multiplied by R. We know the current is two

Amps so we can write that in and we know the resistance is three Ohms, so we can write that in also. Therefore, two Amps

multiplied by three Ohms, gives us six volts. The battery is therefore six volts. Now, if you want to check your

answers for Ohm’s questions, then I’ve built a free

calculator on the website. You can just drop your numbers in and it will do the calculation for you. Links for that again, in the

video description down below. Coming back to the circuit,

if we now double the voltage by connecting two six volt

batteries in a series, we get 12 volts. If we now connect this

to the same circuit, the current also doubles

from two Amps to four Amps. If we double the voltage

again to 24 volts, the current will also

double to eight Amps. So, what’s the relationship here? We can see that current is therefore directly proportional to voltage. If we double the voltage,

we double the current. Remember, voltage is like pressure, it’s the pushing force in the circuit. It pushes the electrons around the wires and we place things like lamps

in the way of these electrons so that they have to flow through these and that causes the lamp to light up. By doubling the voltage we see that the current also doubles, meaning that more electrons are flowing and this occurs as we apply

more pressure or more voltage. This is just like if we were

to use a bigger water pump then more water will flow. Okay, so what about finding current? Let’s say we now have a three Amp lamp connected to a six volt power supply. To find the current, we write down I=and then we cover up I in the triangle. That gives us V divided by R, so current equals voltage

divided by resistance. We know the voltage is six volts and the resistance is at three Ohms, so the current is therefore two Amps and that’s what we see on the multi-meter. By the way, if you

don’t have a multi-meter then I highly recommend you get one. It’s essential for troubleshooting, but also building your

essential electrical knowledge. I will leave some links down below for which one to get and from where. So, we saw what happens

when we use a resistance of three Ohms in the circuit, but if we double the

resistance to six Ohms by placing another three

Ohm lamp into the circuit, the current halves are just one Amp. If we double the resistance

again to 12 Ohms, the current will half again to .05 Amps. We can visually see this because the lamps will become less bright

as the current reduces from the increase in resistance. So, what’s the relationship here? We can see that the current

is inversely proportional to the resistance. When we double the resistance, the current will decrease by half. If we half the resistance

the current will double. Current is the flow of electrons or the flow of free electrons. For us to make this lamp shine, we need to push electrons through it. How do we do that? We apply a voltage across the two ends. The voltage will push the electrons. The atoms inside the copper wire have free electrons in

their valance shell, which means they can very easily

move to other copper atoms. They will naturally move to

other atoms by themselves, but this will be in random directions, which is of no use to us. For the lamp to turn on, we need lots of electrons to

flow in the same direction. When we connect a voltage source, we use the pressure of a

battery to push the electrons through the circuit all

in the same direction. For example, to power this

1.5 Ohm resistive lamp, with a 1.5 volt battery, requires one Amp of current. This is equal to six quintillion, two hundred and forty

two quadrillion electrons passing from the battery and through the lamp every second. And if you can achieve this, then the lamp will stay

at full brightness. If the voltage or current reduces or the resistance of

the circuit increases, then the lamp will become dimmer. Okay, now let’s look

at finding resistance. Say we have a resistive lamp connected to a 12 volt power supply. We don’t know how much resistance

is adding to the circuit, but we measure the current at 0.5 Amps. To find the resistance, we write down R=and then we cover up

the R in the triangle. We’re left with V and I, so resistance equals

voltage divided by current. We know the voltage is 12 volts and the current is 0.5 Amps, so 12 divided by 0.5 gives

us 24 Ohms of resistance. Resistance is the opposition

to the flow of electrons. It tries to prevent

electrons from flowing. That’s why we use resistance in circuits to reduce the current and protect

components such as an LED. If we tied to connect an LED directly to a nine volt battery, it would blow out because the voltage and

the current are too high. But, when we add a

resistor into the circuit, then these are reduced, so the LED is protected

and will shine brightly. So, given the circuit, we

can increase the current by increasing the voltage. Or we can also increase the current by reducing the resistance. We can also reduce the current

by increasing the resistance. Okay, time for you to test your skills. Can you solve these problems? I will leave a link for

the answer and the solution in the video description down below. Problem one: Let’s say we have this lamp which has a resistance of 240 Ohms. If we plug this into an outlet in the US, which uses 120 volts, what will the current be? Problem two: If I plug the same 240 Ohm resistive lamp into an outlet in the UK, we get a current of 0.958 Amps. So, what is the voltage

being applied here? Okay guys, that’s it for this video, but to continue your learning then check out one of the

videos on the screen now and I’ll catch you there

for the next lesson. Don’t forget to follow us on Facebook, Twitter, Instagram, LinkedIn, as well as theengineeringmindset.com

⚠️

Found this video super useful?Buy Paul a coffee to say thanks: ☕PayPal: https://www.paypal.me/TheEngineerinMindset

Whoop! 4am. First view!

If only these videos existed when I was in school.

Sir, this is Amazing. Great job !!!

Dude I absolutely love your videos, so clearly explained & well edited!

double the voltage automatically doubles the current (1amp=1coulomb)

FOR a GIVEN resistance. Current in a given conductor is LIMITED to the

diameter of the wire. Great basic video. Thank you.

Best engineering teaching channel

Sometimes science is just turtles all the way down:

'Why do engineers use (j) = sqrt(-1) instead of (i)?'

'Because 'i' was already taken.'

'What is 'i' used for?'

'Current.'

'Why do we use 'i' for current? Why not 'C'?'

'Because 'C' was already taken…'

Incredible with classic touch !

Thank u for uploading

This will come in handy

Thank you

The German physicist was obviously part of the "RESISTANCE" to the establishment in his time 🙂 LOL

V = IR

Thats all you need to remember.

Thanks 🙏🙏🙏🙏🙏please . I need for purifier separator

PURIFIER tutorial

Mitsubishi purifier oil separator

Please teacher,🙏🙏🙏🙏

Your taste in multimeters is great. I wish I had this video about 2 years ago, it would have helped immensely.

Great explanation. I like to visually remember it as a water dam. Current being the water flowing, resistance being the dam, and voltage is the resulting buildup of water that can't pass.

Here in Germany we use U for voltage and V is only the unit.

How can we find the resistance of battery?

Your work is as always MUCH appreciated. THANK YOU👍🌟🌟🌟🌟🌟

👍

That's awesome sir 👌😊✌️

Nice video … Thanks for helping others.

You really only need to learn one equation v= i r

Then do basic math if you need the other two right?

Great video to keep the basics fresh. I know it’s a good few steps ahead but do you have any plans to do videos on Kirchhoff and Thevenin?

Excellent video! Thank you it is very helpful.

Ohm's law only applies to circuit elements that are ohmic. That's all you need to know.

Usually use Ohms law to find watts for power consumption, or kilowatt hours that are billed to you from the power company. I'm an HVAC/R Tech and business owner. I recommend your videos to all my up and coming techs and even the veterans too.

sir please make vidoes in electronics

Thank you so much for all your videos.

Go on! I love your videos!

thanks sir

For some reason I thought the current went down when you increased voltage. And that is why people prefer to have 240v things because it's more efficient? Or cheaper? Less current I thought since I believe we are charged in watts [VoltAmps] over time. For the same load, If we double the voltage and that in turn doubles the current, then wouldn't we be charged a lot more on the electric bill?

George was out there doing the work.

Useful video clip

Always perfect. Thank you…

Thx man

Please keep making these kinds of videos Sir! You are a great teacher.

Assumes everyone knows nothing.

Finally a video for me!

If only these videos existed when I was in school.

EK HI DIL ❤️ H SIR KITNI BAAR JEETOGE.

Without your Videos Sir YouTube is boring 😀😀

In industrial electrical 3 phase motor if 380A each line how much it all? How to compute this I need to know.

one of the best OHMs videos on youtube

Corrrct 8:39 w " When we had a greater resistor " or something or had the Imax and led can handle

Could you make a video about 5 pins dc relays?

We could use a whole long video on parallelism and resistance. The electrical resistance of an object is a measure of its opposition to the flow of electric current. The inverse quantity is electrical conductance.