Welcome to my first video on circuits.
In this video I'm going to give you a brief introduction and tell you the difference between
a series circuit and a parallel circuit.
Before I get started let me introduce myself.
My name is Chris.
I am the creator of all the videos here at Math Meeting.
If you need any extra help with your homework send me pictures of your homework problems
to my email in the right hand part of the screen.
And I will get back to you immediately with a quote if you want homework solutions.
If you want live tutoring send me an email to Math Meeting.
Let's not waste any more time and let's get started with this video.
Let's start on the left hand side of the screen and talk about a series circuit.
And the reason why it's a series circuit is because all of these resistors, these squiggly
lines, they are all in series with each other.
So that's why it's called a series circuit and I want to talk about the main differences
between a series circuit and a parallel circuit.
The first thing I will talk about is current.
The current in a series circuit is always going to stay the same.
You should write this down.
The current in a series circuit is always going to stay the same.
Let me show you what I mean by this.
Let's start with the power source or the battery.
The current leaves the positive terminal of the battery and enters in the negative terminal
of the battery.
It's going to flow in a clockwise direction.
So let's call the current at the top left side of this circuit.
We'll call this I1.
Current is written with the letter I.
The current is going to flow through this first resistor and then we'll call the current
in the top right hand part of the screen.
We'll call it I2.
So once again the current is always going to stay the same.
So I1 is going to be equal to I2.
The current at point 1 is going to be equal to I2.
So after it flows through this first resistor the current is not going to change.
For this entire series circuit the current is going to be exactly the same.
So now let's talk about the current flowing through a parallel circuit.
So once again the current is going to flow from the positive terminal of the battery
to the negative terminal.
So it's going to flow in a clockwise direction.
So this current which I'll label the current in thee top left part of the circuit.
We'll call this I1.
And the current is going to reach this junction or this node.
Then after it gets to this node it's going to split off.
Part of it is going to go down this left side into this left resistor and part of it going
to go down the right side and go down in to the right resistor.
So let's label the current going through the left resistor.
We'll call this I2.
We'll call the current going through the right resistor.
We'll call this I3.
These currents I2 and I3 they are not the same as I1.
The current for a parallel circuit is not the same through out the circuit.
You should write this down.
The current for a parallel circuit the current is not the same through out the circuit.
The total current though is not going to change.
The current I1 is going to split off.
It's not going to change because I2 and I3 are going to be equal to I1.
So when I1 splits off, it's going to split off into I2 and I3.
That total current is going to be equal to each other.
So I1 going to be equal to I2 and I3.
And the values for I2 and I3 are going to be dependent upon these resistors.
Depending on how much or how little resistance there are in these resistors is going to determine
how much current is in I2 and how much current is in I3.
So now let's talk about voltage.
Once again we'll start with our circuit that is in series.
The one thing we have to remember for a series circuit.
The voltage change is not equal across the resistors.
So let me show you what I mean by this.
So let's say this battery has a voltage of 12 volts.
Which means that leaving the battery we know before it crosses the first resistor.
It's also going to be 12 volts.
But there is going to be a voltage change when it crosses this resistor.
So we'll call the voltage after it crosses the resistor.
We'll call this V1.
We don't know how much that change is.
We don't know what the voltage is at this point because we don't know the resistance
of these resistors.
And we don't know the voltage at V2.
Because once again we don't know the resistance.
But the voltage is not equal.
It is dependent upon these resistors.
So it could go from 12 to 9 volts at V1.
Then at V1 it can go from 9 volts to 2 volts at V2.
The one thing we do know is the voltage right before it enters the battery.
It's going to be equal to 0.
So now let's talk about the voltage in a parallel circuit.
So once again let's say that we have a 12 volt battery.
Which means we know the voltage in the top left corner of the circuit is also going to
be equal to 12 volts.
Which also means that the voltage at this node is also going to be equal to 12 volts.
Because we have not crossed any resistors at this point.
And we know that the voltage over here is also going to be equal to 12 volts.
Because once again we have not crossed any resistors.
Once again we know that the voltage right before it enters the battery is going to be
equal to 0 volts.
Which means the voltage over here is also going to be equal to 0 volts.
And the voltage over here is going to be equal to 0 volts.
because we have not crossed any resistors.
And now notice the voltage change across this first resistor goes from 12 to 0.
And the voltage change across this second resistor also goes from 12 to 0.
So they are exactly equal to each other.
So the voltage change from two resistors in parallel.
The voltage change is equal from two resistors in parallel.
So I hope this gave you a better idea on the difference between a series and parallel circuit.
In my next video I'm going to talk about how we solve series and parallel circuits.
And the different equations that we use to solve them.
And we'll talk about the different current and voltages that go through each resistor.
So I hope you enjoyed this.
Once again I do provide live tutoring and homework solutions.
My email addresses are on the right hand side of the screen.
Or you can check out my website at Math Meeting.
Thank you so much for watching and I will see you in my next one.