Lesson One

TOPICS:
Atoms
Electrons
Current

What is voltage, current, and resistance?
When you turn on a light in your home. When you run the vaccum. What is realy happening. It all starts with the atom. Dosen't it always. The atom is made up of electrons which orbit or spin around a thing in the center called the nucleus. Electrons have a static charge similar to the type of charge your hair gets when you roll around on the rug with your dog!.Electrons(the yellow things) are charged nagative(-) and protons, the things which make up the nucleus are charged positive(+). Like magnets the nagative electrons are attracted to the positive protons. The number of protons in the nucleus is equal to the number of electrons spinning around the nucleus. It's a perfert balance. In the adjacent diagram the yellow electrons are spinning around the two protons in the nucleus.

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TOPICS:
Atoms
Electrons
Current
Voltage

So what does all this have to do with current and voltage?
Get a better browser! Well, if one of those there electrons gets knocked out of its orbit, the positive charge OF TWO PROTONS hungers for the negative charge OF TWO ELECTRONS. The atom will then pull in any electron which happens to float by. If things are just right, and the electrons cooperate, we can cause the following to occur: Look at he adjacent diagram. On the left is a group of electrons. Very Very negative this bunch! On the right is a group of protons. They're positive. So positive is this bunch of protons that they will pull in the closest electron which happens to be in the atom closest to the protons. This atom in return will take an electron from the atom closest to it, who in return will take one from the group of electrons on the left. This process will continue until all the electrons have made their way over to the protons. PLACE YOUR MOUSE ON THE ELECTRONS in the adjacent diagram. THIS IS CURRENT! The movement of electrons in a somewhat organized path. Well it's not exactly this simple, but what do you want from a free tutor!

So what exactly is VOLTAGE?
If the number of electrons and protons in the foregoing diagram were increased, then the electrons would be attracted to the protons with an even greater force. The result would be some fast moving electrons! So, if you increase the number of electrons on the left and protons on the right, you are increasing VOLTAGE. This will result in faster moving electrons. Which means more CURRENT. Get it! More voltage means More current.

So how do you control current
Current is out of control. Like a two year old, current does what it wants. To slow it down you could: remove the voltage, or put something in its path like a light bulb or a RESISTANCE

What in the world is a resistance?
There are some materials that slow down electrons. Wood! Electrons don't like wood its like a road full of potholes. Copper, electrons love to speed through copper. Its like a super highway. So, to slow down current put some resistance in its way. Give it a super highway(copper) but throw in some potholes. Resistance can come from: light bulbs, Motors, resistors and a bunch of other stuff. In fact you can buy things called resistors. They look like this:Where am I To determine how much current is in a piece of wire you can use the following relationship:VOLTAGE(V) divided by RESISTANCE(R) equals CURRENT(I). Yes use (I) for current. V/R = I. In the example below, a 9V battery is connected to a resistor with some copper wire. In the center of the drawing is something called a schematic diagram. Each part of the connection has a symbol. The voltage is 9V the resistance is 1000 ohms. Yes Gas comes in gallons, resistance comes in ohms, current in amps, and voltage in volts. Can you determine the current in the wire? Get out the calculator and REMEMBER!!! V/R=I.

1:
In the adjacent diagram, The amount of current flowing in the wire will be:



A: 1.000amp
B: 0.009amp
C: 0.001amp
D: 9.000amp
Battery and resistor .I
TOPICS:
Atoms
Electrons
Current
ACV

So what do they mean by AC voltage?

Well, in AC electrons travel in one direction for a certain amount of time and then they reverse direction. They do this over and over a number of times per second. If the electrons change direction 60 times in one second, we would say "the AC is running at 60 hertz". But, don't fear, AC voltage, current, and resistance are related in the same way!
In the following example a light bulb has a resistance of 240 ohms (yes, light bulbs have resistance too!) It is drawing current from a 120V outlet. Do you thing you can answer this complex mathematical question! OH COME ON. TRY IT!

2:
In the adjacent diagram a 120V outlet is supplying current to a 240 ohm light bulb. How much current will be in the bulb?



A: 0.900amp
B: 0.009amp
C: 0.500amp
D: 5.000amp
AC voltage with bulb
and switch.
.I
TOPICS:
Atoms
Electrons
Current
ACV
Parallel

So how are multlple outlets in my home connected.

Well, if you were to connected them one after the other, and plug in three lights. The connection would look somthing like the adjacent figure: But, if you were to turn off one light or remove one bulb, the current to all the bulbs would stop. Get a better browser! PLACE YOUR MOUSE ON THE BULB ON THE LEFT! Since electrons must travel through one bulb to get to the next, current will stop everywhere. Similair to opening a draw bridge on a busy road! This connection is called a series conection (one after the other). In this type of connection the voltage will divide up among the bulbs. Each bulb will feel a voltage force of 40Vac . The resistance of each bulb would add to form a single total resistance. If each bulb had a resistance of 240 ohms, then the total resistance in this connection would be: 720 ohms. To now determine the current in the loop use: Total voltage (120) divided by total resistance (720). Once again it's: V / R = I.
Obviously, you wouldn't want to connect the outlets in your home in THIS WAY! But this type of connection does have its place. Try to solve the following problem.

2:
In the adjacent diagram a 12V battery is supplying current to three resistors. How much current will be taken from the battery?



A: 0.900amp
B: 0.009amp
C: 0.500amp
D: 5.000amp
Battery and
three resistors.
.I
TOPICS:
Atoms
Electrons
Current
ACV
Parallel
Outlets in your home are connected so that each bulb, resistance, or whatever, keeps recieving current when a second bulb is unpluged. This is achieved by connecting the outlets as follows: The adjacent diagram shows three resistors connected in what is referred to as a parallel connection. If one of the resistors is removed the current still has a clear path from the posative of the source back to the negative. Hey, if somthins in ya way, go around it!. If you take a good look at this connection, you will see that each resistor is connected directly across the 12V source. Thus! each resistor feels a voltage of 12V. Guess what! You can calculate the current. How you ask? Oh come on, you know how. V / R = I The current in the 100 ohm resistor can be found by dividing 12V by 100 ohms. The current in the 200 ohm resistor can be found by dividing 12V by 200 ohms. The current in the remaining resistor is found in the same way.
The three currents could then be added together to determine the amount of current taken from the voltage source. Try to solve the problem below:
2:
In the adjacent diagram a 12V battery is supplying current to three resistors. How much current will be taken from the battery?



A: 0.900amp
B: 0.009amp
C: 0.500amp
D: 5.000amp
Battery and
three resistors.
.I