I am Kareen, I am a student and I am currently pursuing a degree in Electronics Technology. I decided that the best way to learn is by sharing what I just learned; it gives me a chance to really understand the subject if I have to explain it to someone else. I am in no way a subject matter expert in this area, I am merely a beginner. Every time I cover a chapter on my book (Foundations of Electronics, 5TH Edition by Russel Meade), I will post a corresponding link so others can study along with me, post suggestions, ask questions, and post answers. Because I am using a book and posting a corresponding link, this will be a structured study guide for those who want to learn electronics outside of the classroom.
Chapter 2 is now finished. Here is the link to Chapter 2.
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Step 1: The Atom
Electronics is concerned with manipulating the movement of electrons, therefore, It is important to begin our study with investigating the atom. All matters (anything you can see, feel, taste, hear, smell, and even things that are invisible to human senses) are made up of atoms.
The Atom has sub particles that is particularly of interest to electronic technicians and engineers. This is because one of the sub particles of an atom is the electron, which as stated above is the basis of electronics. The other sub particles of an atom are, protons and neutrons, which are located in the nucleus. It is important to understand these sub particles and how they interact in order to manipulate them.
Click on the yellow square to find out more about the atom.
Step 2: Atomic Charge
Each atomic sub-particle has a specific charge. The electron has a negative charge, the proton has a positive charge, and the neutron is neutral or has no charge.
Click on the yellow square to find out more about the atom.
Step 3: Atomic Shells
The atom consist of shells, and each shell can only be occupied with a specific number of electrons. The formula to find how many electrons can occupy a shell is 2(n)^2 or the squared of n times 2.
In this formula, "n" stands for positional number of shell from the nucleus. The first shell is called Shell 1 because its closest to the nucleus. In order to find how many electrons can occupy Shell 1 we must use the formula 2(n)^2.
Shell 1 2(1)^2 = 2 electrons
Shell 2 2(2)^2 = 8 electrons
Shell 3 2(3)^2 = 18 electrons
Shell 4 2(4)^2 = 32 electrons
So for Shell 1, a maximum of 2 electrons can occupy it. Because 2 is the maximum, shell one can have just 1 electron on it or no electrons at all. This applies to the other shells as well.
Remember that an atom can have an infinite number of shells. However the last or the outermost shell can only contain up to 8 electrons.
Step 4: Ions and Isotopes
Click on the picture to see the other.
In the process of intermingling with other atoms, some atoms loose their electrons, and some gain more electrons. Atoms with 3 or less electrons in their outer shell are easily moved.
****Negative Ion is when an atom has more electrons than its protons.
****Positive Ion is when an atom has more protons than its electrons.
Another interesting characteristic of elements/atoms in their sub atomic composition is the isotope. To determine that an atom is of the same element (for example carbon) they must have the same number protons. Carbon has 6 protons. Accordingly, an atom with 6 protons and 6 or more neutrons is also carbon, more specifically a carbon isotope, or in other words variation of the base carbon atom (with just 6 protons).
An isotope therefore is an atom that is a variation of another atom with the same protons. Consider Carbon 12 and Carbon 14 on the images.
Carbon 12, has 6 protons
Carbon 14 has 6 protons
------the difference between these 2 isotopes can be seen in their number of neutrons.
Carbon 12 has 6 neutrons
Carbon 14 has 8 neutrons.
Carbon 12 and Carbon 14 are isotopes of Carbon.
Also generally, when there are 6 protons, there will also be 6 electrons, in a neutrally charged atom.
***This part of the lecture is just for your information and does not require memorization.
Step 5: Conductors, Semi-conductors, and Insulators
For the purpose of the ease of moving electrons, matters are categorized as conductors, semi-conductors, and insulators. Conductors are materials like silver, copper and gold, among many things. Semi-conductors are materials like silicone and germanium. Insulators are materials like glass and ceramic. It is important to know these materials because they are often used to make electronic components.
Conductors have atoms that only have 3 or less electrons in its outer shell. This makes it easier for electrons to flow.
Semi-conductors have atoms that have 4 electrons in its outer shell. This creates resistance against electron flow.
Insulators have atoms that have 5 or more electrons in its outer shell. This does not allow electrons to flow.
Click on the images, to see examples of conductors, semi-conductors and insulators.
Step 6: Reflections With Cat Vader
Okay, so far we've covered 5 topics;
1. The Atom
2. The Atomic Charge
3. The Atomic Shell
4. Ions and Isotopes
5. Conductors, Semi-conductors, and Insulators
Important things to remember for an aspiring Electronics Tech;
1. Electronics is concerned with the manipulation of electrons.
2. Atoms are made up of sub-particles: Electron, Proton, and Neutron.
3. Electrons have negative charge, Proton is positive and Neutron is neutral or no charge.
4. A conductor has 3 or less electrons in its outermost atomic shell.
5. A semi-conductor has have 4 electrons in its outermost atomic shell.
6. An insulator has 5 or more electrons in its outermost atomic shell.
7. Conductors allow the flow of electrons with ease.
8. Semi-conductors produce resistance to electrons, which controls how much electrons can flow through them.
9. Insulators do not allow electrons to flow.
More is to come, may the fur be with you.
Step 7: Basic Law of Electrical Charges
Most of you have probably heard of the saying, "Opposites attract." If you have, congratulations, you now know one rule in the Basic Law of Electrical Charges. More specifically, the Basic Law of Electrical Charges holds that Opposite charges attract and like charges repel.
Now, what does this mean to you? well, this means that two materials with both negative charge, when place against each other (side by side), will naturally move away from each other without your help. Congratulations, you have just discovered telekinesis ( :p not). Accordingly, two materials with different charges (1 positive and 1 negative), when placed in proximity with each other, will naturally move towards each other!
Now, how about thinking of practical applications for this specific discovery? moving materials with minimal human intervention? think about ettttttt. yes! see you're a genius! good job.
More importantly, this gives you a clue on how electrons can move from one place to another; say from the power station to your house. Don't get fuzzy with me, answers come later.
To understand more about this attraction, please visit this link http://wiki.answers.com/Q/What_happens_to_the_electric_force_of_attraction_between_an_electron_and_a_proton_as_they_approach_one_another
Step 8: Practical Experiment, Opposites Attract, Like Charges Repel
Now for this experiment we will demonstrate that "Opposite Charges Attract, and Like Charges Repel."
For this experiment, you will need:
2 balloons (available at Walmart by the card and party section for around $1)
1 unsuspecting pet or sibling or if u want to play risky, 1 unsuspecting stranger
There, if you can't afford that, go to wazoos, there is destined to be a toddler there yanking around a balloon. No, I'm not suggesting that you kidnap the kid, I mean beat the kid in a game of rock, paper, scissors to win the balloon.
After you've acquired and fulfilled all of the pre-requisites, you are now ready to follow these steps.
Step 1. Pump air into the 2 air balloons. I don't care how you get air in there, as long as it is legal.
Step 2. Acquire your target. If you're a loner like me, that will be yourself.
Step 3. Aim for the head.
Step 4. Rub 1 balloon furiously on the targets head for 4 seconds, or if it pleases you, keep on it until your arm hurts.
Now, what do you observe? Does your hair stick to the balloon? If it does not, it's the balloon's fault, repeat Step 4. If it still does not stick to your hair, then you're probably bald. If your hair does stick to the balloon, congratulations, you just won yourself an explanation;
Remember when I said generally materials are balanced or neutrally charged (has the same amount of protons as electrons)? Well, it just so happens that your hair and the balloon are neutrally charged prior to you rubbing them with each other.
When you started rubbing the balloon with your hair, your hair lost the electrons to the balloons with the aid of friction. Now, this means that your hair is no longer neutrally charged, because now its electrons and protons are no longer the same quantity. The balloon stole the electrons from your hair, which means now you have more protons than electrons on your hair, and this makes you positively charged.
Remember in math when the positive number is bigger than the negative number, if you combine them together, the answer would be positive? Well, the same principle applies to your hair, now that the number of protons (positive) is bigger than the number of electrons (negative), when combined, the result (your hair) becomes ultimately positively charged. Okay, so we got that down, your hair is now positively charged.
Okay, my explanation is only half way there, so bare with me. Here's the second half.
Well, because the balloon acquired the electrons from your hair, now the balloon has added more electrons to itself. This means, that the balloon now has more electrons than protons. This means that the balloon is no longer neutrally charged, because remember what neutrally charged means? You're right, neutrally charged means, that the material has to have the same amount of electrons as protons. Well, obviously the balloon fails to meet that criteria.
And because the balloon has more electrons (negative) than protons (positive), it is now considered negatively charged. It behooves you to remember , that in math, when combining a bigger negative number with a smaller positive number, the answer becomes negative. The same principle applies to the balloon, now that the number of its electrons are bigger than the number of its protons, when combined, the balloon becomes ultimately negative. Okay, now, so we got that one down too, the balloon is now negatively charged.
Okay, so let me get this right, the hair is positive and the balloon is negative?
Goodness gracious, that's why your hair is attracted to that balloon! look at them all intertwined, like lovers that haven't seen each other in years! And yes, if you remember, the rule "Opposites Attract," that is why the balloon and your hair are drawn to each other. Okay, now, now, calm yous a44 down. We've only proven part of that rule, we still have to prove the other part, which is like charges repel.
To prove that like charges repel, you have to repeat Steps 1 through 4. And then follow the steps below;
Step 5. Tie each balloon with a string, then tie their strings together as demonstrated in the image provided.
Step 6. Hold the balloons in front of you while making sure that they're not touching any surface.
Now, assuming you did not pump the balloons with helium, the balloons should be hanging down towards the floor. Now, what do you observe? are the two balloons not touching each other? even when you put them side by side? Well, here's the explanation for that.
Remember, that the balloons after going through steps 1-4 became negatively charged. Well, now what you've got in your hand are two balloons that are both negative, that is why they are avoiding each other like a plague. Because remember the other rule? Correct! Like charges repel. Now go on your merry way and have a soda can race with that balloon.
Step 9: Polarity and Reference Points
To identify whether a certain point is negative or positive, you must have a reference point for it. That is to answer the question, it's negative/positive in comparison to what?
The signs (-) or (+), when used in electronics, are called polarities. Going back to our previous lecture, when we call something positively charged, it means there are more protons. Another true statement would be, that it is positively charged because it has more protons and less electrons. Well, we want to focus on the fact that it has less electrons, as the reason for its positive polarity.
However, polarity does not stand alone by itself, it is (+) or (-) because it is compared to something else. An accurate definition would be that an object (or a point in an object) can be considered positive if it has less electrons than another object (or point in an object). Correspondingly, an object (or a point in an object) can be considered negative if it has more electrons that the other object (or point in an object).
To understand this better, look at the image provided in this lecture. In the image, what point do you think is positive? What point do you think is negative?
If you answered Point A for the first question, then you are correct!
If you answered Point B for the second question, then you are correct again!
Here are the important points;
1. When an object has more electrons than another object, it is negative.
2. When an object has less electrons than another object, it is positive.
Step 10: Sources of Electrical Energy
Electrical energy is produced when there is a change in the electrical balance of atoms. That is to take neutrally charged atoms and add or take away its electrons in order to render it unbalanced or no longer neutrally charged.
There are many ways to create this electrical imbalance in order to produce electricity;
1. Heat/Thermal - an example would be a thermocouple (google it)
2. Magnetism - an example would be magnet motors.
3. Chemical - an example would be batteries.
4. Mechanical/Motor - an example would be generators.
5. Light - an example would solar cells.
6. Friction - an example would be seismic energy dissipation devices.
There, so if you were wondering how electricity is produced, it is through manipulation of electrons and inducing an electrical imbalance in atoms.
Step 11: Reflections With a Young Jedi
Okay, so far so good, we're almost done with Chapter One, hazaaaa!
So far we've covered additional topics;
1. Basic Law of Electrical Charges
3. Polarity and Reference Points
4. Sources of Electrical Energy
Important things to remember;
1. Opposites Attract, Likes Repel
2. You can do that experiment too
3. Negative has more electrons (in comparison to)
4. Positive has less electrons (in comparison to)
5. Electrical Energy can be produced from inducing an electrical imbalance in atoms.
Another day, another bacon.
Step 12: The Force of Attraction and Repulsion
Opposite charges attract and like charges repel. When two objects of like charges are placed in proximity of each other, how far do they repel each other? When they are of opposite charges, how close do they move towards each other?
What determines how much force of attraction or repulsion is between two charged bodies?
Allow me to introduce a friend of mine, Charles Coulomb. My dearest friend Mr. Coulomb found out that the force (F) of attraction or repulsion between two charged bodies is:
directly related to the product of their charges and inversely related to the square of distance between them.
F = charge 1 x charge 2
In honor of my friend, Charles Coulomb, the unit of charge, the symbol Q, is called the coulomb.
Unit of charge : Q (coulomb)
How many electrons are in 1 coulomb you say?
That is 6, 250, 000 , 000, 000, 000, 000 electrons
6.25 X 10^18 electrons
What can we find from this rule?
Well, when the two charges are higher, the force to which they can attract or repel each other is also higher.
That is what is meant by directly proportional. F is higher when Q1 and Q2 is higher.
It is because we multiply the two charges, when we multiply things, the result becomes bigger.
And notice that in the equation, F is directly across Q1 and Q2? This means that whatever happens to Q1 and Q2, the same exact thing happens to F.
So if Q1 and Q2 goes up, well you guessed it right, F also goes up.
Also, when the distance is longer between the two charged objects, the force to which they can attract or repulse each other decreases.
Which is what is meant by inversely proportional. F is decreased when distance is increased.
It is because we divide by distance, so of course when we divided something, the result becomes smaller.
Notice that in the equation, the distance is below F? This means that when distance changes, the opposite of that change happens to F.
So if distance goes up, F goes down.
F = Q1 x Q2
Step 13: When Does Your Battery Run Out of Charge
1. Any substance or body that has excess electrons is negatively charged.
2. Any substance or body that has a deficiency of electrons is positively charged.
The ability/potential of electrons to move based on polarity and electron deficiency has several names:
emf or electromotive force
But remember, it just an ability. It becomes actual movement only when a path is provided, i.e. a copper wire.
So, when you purchased a brand new battery, the positive is one side of the battery, and the negative is on the other.
What makes the positive side of the battery more positive than the other side, is because it has fewer electrons in comparison. Accordingly, what makes the negative side of the battery negative more than the other side, is because it has more electrons in comparison.
Now, when we connect one side of a wire to the positive terminal, and the other side of the wire to the negative terminal, what happens is, we provide a path for the electrons to travel.
This movement of electrons will continue until the amount of electrons on each side of the terminals are equal. This is when your battery is considered out of charge.
Want to recharge your battery out in the desert? Let it soak in the sun all day. Okay, now it wont fully recharge, but it will recharge some. How does this happen you say?
Assuming that the casing of your battery is a conductor (example: some sort of metal) this method should work on most AA, AAA cells and 9V batteries. The sun supplies the additional electrons to recharge your batteries.
But there is no wire from the sun to the battery, so how do the electrons travel to battery? We forget that, although the air is a poor conductor, it is still a conductor. The air provides the path for electrons to travel from the sun to the battery.
Now, that I think about, the space where the sun is has no air. So how do the electrons travel from the sun to earth?
Maybe in this case the electrons didn't need air to travel, maybe it just needed space. Sounds to me like you have some researching to do.
How is the sun burning without air? I thought in order to create fire, there has to be air. Ever lit up a candle and covered it entirely with a jar? Doesn't it die afterwards? If space has no air, then where is the sun getting the air to burn? Did it suck all the air out of space in our solar system? Is this why there is no air in outer space?
Step 14: Electrical Quantities and Electron Flow
The Three Important Electrical Quantities involved in Ohm's Law:
1. Voltage - which is measured in volts
2. Current - which is measured in ampere
3. Resistance - which is measured in ohms
Now, we have mentioned earlier that:
Voltage is the ability of electrons to move based on polarity. And to be electrically accurate, it is the potential difference between two points (the positive and negative terminals).
Then what is current? In that voltage is the ability,
Current is the actual movement of electrons. In simple terms, voltage is the doer and current is the action. Current is simply the electron flow.
How about resistance? What is resistance?
Resistance is the amount of opposition/resistance to electron flow.
Another important question in the scheme of things is, which way do electrons flow?
Electrons flow from negative to positive. In the case of a circuit or battery, that is from the negative side of the terminal to the positive side of the terminal. To understand this better, look at the image provided for this lecture.
Step 15: Ohm's Law
There are three important people involved with the creation of Units of Measurement;
Alessandro Volta - the unit measurement of voltage, which is VOLT, is named after him
Andre Marie Ampere - the unit measurement of current, which is AMPERE, is named after him.
Georg Simon Ohm - the unit measurement of resistance, which is OHM, is named after him.
Symbols of the Three Units of Measurement;
The symbol for volt is V. So when we say five volts, we can write 5V. You must capitalize. It is V and not v.
The symbol for ampere is A. So when we say five amperes, we can write 5A. You must capitalize. It is A and not a.
The symbol for ohm is Ω. So when we say five ohms, we can write 5Ω.
The Ohm's Law
Georg Simon Ohm, through his work, observed that there is a predictable result in the relationship between voltage, current and resistance. He discovered that:
1. Voltage is directly proportional to the product of current and resistance. V = I x R.
So if we want to find how much voltage is in a circuit with a current of 5A and the resistance of 5Ω, we must use the formula V = I x R.
V = 5A x 5Ω
V = 25V
2. Current is directly proportional to voltage and inversely proportionally to resistance. I = V / R
So if we want to find how much current is flowing in a circuit with 10V and 5Ω, we must use the formula I = V / R
I = 10V divided by 5Ω
I = 2A
3. Resistance is directly proportional to voltage and inversely proportional to current. R = V / I
So if we want to find how much resistance is in a circuit with 5V and 10A, then we must use the formula R = V / I
R = 5V / 10A
R = 1/2 Ω
R = .5 Ω
In the image provided with this lecture, the ohm's is depicted in the triangle. Drawing the ohm's law in a triangle is the easiest way to remember all of the three laws.
In the image, the triangle has three parts. The top half belongs to V or voltage. The second half is parted in to two. The left side belongs to I or current and the right side belongs to R or resistance.
Now, if you want to find voltage, then cover V with your finger, which is the top half of the triangle. Now you are left with I and R. And because I and R are in the same level, you have to multiple them, (I x R).
If you want to find current, then cover I with your finger. You should be left with V and R. Since V and R are in different levels, (one is on the top half and the other is on the bottom half), then you must divide them V / R.
If you want to find resistance, then cover R with your finger. You should be left with V and I. Since V and I are in different levels, you must divide them, V / I.
If you remember to draw this special triangle, then you will be likely to remember ohm's law each and every time you need it.
Step 16: Basic Electrical Circuit
A basic electrical circuit has several components;
Although not necessary, it may have a control element, such as a switch.
An example of this would be a circuit that contains a 9V battery as a source, a resistor or LED as the load, a copper wire as the conductor path, and a switch as a control element.
There are two terms you must familiarize yourself when it comes to circuits.
1. Open Circuit
2. Closed Circuit
An open circuit is when there is a break in the path of current. For example, a break in the electrical wire. This means that there is no complete path for the current to travel from the negative side of the circuit to the positive side of the circuit. When current cant travel, well, there is simply no current or more frankly, there will be no electricity.
A closed circuit means that there is no break in the path of current. This means that there is a complete path for the current to travel from the negative side of the circuit to the positive side of the circuit. Furthermore, when current can travel, there is bound to be electricity.
Step 17: This Is the End of Chapter 1
This is the end of Chapter 1. Give yourself a path on the back and grab an apple. Chapter is completed. Here is the link for Chapter 2:
Chapter Summary Quiz
1. What is electronics?
2. What are the sub particles of an atom?
3. What is meant by neutrally charged?
4. What is a conductor?
5. What is a semi-conductor?
6. What is an insulator?
7. What are the components of a basic electrical system?
8. What is the basic law of electrical charges?
9. What is meant by electron deficiency?
10. What is meant by positively charged?
11. Which direction do electrons travel?
12. What is voltage?
13. What is current?
14. What is resistance?
15. What is Ohm's Law?
Answers can be found in your memory. Hope you remembered :P