You should not be reading this if you have not completely read Part I of the Basics of Electronics.  If you have read it, no problem, let's continue.

Understanding Basic Circuits, and studying the relationships between resistance, volts and amperes.  More on WATTAGE.  Conductance/MHOS/Siemens.

First I will kinda talk about some quick facts and then we will go deeper into the heading of this chapter.

Most of the time when working with electronics you will be using batteries to make your projects work (D/C circuits) and I strongly recommend that you do until you have practiced and feel comfortable with all this tech ( not to mention safety ) talk before moving into A/C projects.  If you don't practice, you won't learn it.

While working with battery based or cell based projects you should be aware of the difference between SERIES and PARALLEL connected cells to the circuit.

One battery is called a cell, incase you missed that when coming in on the front page of this web site.  Two or more cells is called a BATTERY.

When cells or batteries are connected in SERIES, this means that they are connected end to end.  SERIES connections on batteries in electronics will increase the VOLTAGE of the battery above a single cell.  What that means is, if you connect two cells to a circuit in SERIES, and each of them is rated at 1.5 V, the voltage output will be 3 Volts.

If you connect two cells in parallel, this will keep the voltage output the same at 1.5 V but the total supply of energy and the capacity to produce a given current over a given time will be increased.

SERIES is when cells are connected from plus to minus.  I hope you know what parallel is :- ), but just incase you don't, it simply means, components are connected side by side, + with + and - with -.

One more way exists to connect batteries.  Cells can also be grouped as series of let's say 2 cells, and then connected in with other groups of the same series grouped in parallel.   Imagine that you have 6 batteries, each of them 1.5 V.

You divide these 6 cells into groups of three, you are left with 2 cells in each group which makes 6, right ? follow me ?

Now you connect each of these three groups which are 2 cells in series and then you connect these three series groups in parallel.  This gives you, 3 Volts total with an increased output capacity over time.

George Simon Ohm, the German scientist who lived during the 19th century (1787-1854) is the man who has devoted a good part of his life into the study of PD in electric current and resistance using mathematical relationships.

His LAWS are the foundation of all circuit design and service.  The basics fundamental relationships between VOLTS, AMPERES and OHMS to all studies of electricity and electronics can be credited to him.

There is no more of an important lesson in this field then to understand this fundamental difference and the relationships between the three.

If you fail to understand them, you should stop and read it until you do.

Ok, here we go.   The first fact that you need to know is that:  Electric current in any circuit regardless if it is A/C or D/C; BTW: A/C stands for Alternating Current and D/C stands for Direct Current.  I will explain the difference later, but D/C is used mostly in batteries and A/C is used in high voltage circuits like in your home.

-- is proportional to the applied voltage.  This simply means, that if the voltage is increased, the current will increase.  If it is decreased, the current will decrease.  Current is measured in AMPS, you are still awake, right ?

Second:  The electric current in any circuit is INVERSELY Proportional to it's RESISTANCE.  What that means is if the resistance in a circuit is increased, the current decreases.  If it is decreased, the current increases.

What is the resistance in this circuit ? A resistor ? makes sense ?  What type, doesn't really matter as I am only showing you an example here.

An example now with some numbers.  We have a VERY SIMPLE CIRCUIT.  2 feet of wire, one 10V battery, and a resistor rated at 10 OHMS.  If we measure the current with a meter, we get 1AMPS of current.  If we remove the resistor and place a 5 OHMS in the other's place, what will the current increase to ?

2 AMPS  You can get the same reading by simply increasing the voltage of the battery to 20V instead of replacing the resistor.  If we increase the Voltage to 40V with a 10 OHM R, we get 4AMPS.   I = E/R

You will really learn this once you start doing simple projects designed to teach you to take the right measurements and such.  You should remember atleast one main fact out of all of this mambo jumbo.  That fact is that our little three friends, the VOLT, AMPS and OHMS are kinda linked to each other.  If one's value changes, it will change the other two.

Another new equation for you to study.  This relationship is expressed in an equation like this:

I = E/R

I = intensity of the current in amperes or short AMPS

E = electromotive force in volts, or basically VOLTS

R = Resistance in OHMS

If you have any of the two values you can always find the third one.  Depending on which two values you have you can use three different equations to help you solve for any of the three, they can only be either I, E or R.  If you have I and E, then you are solving for R and you pick the equation with the R on the left side of the equal sign.

I = E/R,        E = I x R     AND     R = E/I

Simple, right ? Good.

Ok, here is a problem if you think it is so simple:

PROBLEM: A current of .5 AMPS flows in a circuit that has a VOLTAGE of 500 VOLTS.  What is the Resistance in the Circuit ?

Well ? PLEASE! Don't make this any harder then what it really is.  This is ELEMENTARY.  You can only have 3 VALUES, E, I or R.  In the above example we have two values already given.  AMPS is I, and Volts is E, so which one is missing ? R  GOOD  We solve for R, and we pick the equation with the R on the left side of the equal sign or R = E/I.

Now it's simple, you simply substitute the E for 500 and I for .5, you divide 500/.5 which gives you 1,000 OHMS.

And the answer is:  The resistance in the circuit is 1,000 OHMS.

I got a question e-mailed to me by a reader, asking me how come everything that he saw in a Radio Shack magazine was rated in WATTS ?

The speakers were rated in watts and so were the CB radios  and such. How come I didn't give more detailed explanation of WATTS and what for example a 1WATT CB Radio stand for ?

To be able to understand WATTS you have to understand this first and that is: VOLTS, AMPS, and OHMS.  I did quickly introduce what WATTS are and such and if you go into PART I you will learn about it.  Once I finish this I will explain in detail why they are rated in WATTS.

The WATT or WATTS is a common unit used to show how much electrical power has been used or a circuit uses.  This brings me to another LAW, this law is called the CONSERVATION OF ENERGY LAW and it goes a little like this:
 

For our poor human souls, this is the law that we have to follow for now.  If you want to be politically correct, use it and you will be fine.  I however don't believe it to be 100% true, but because I am some what of a Cyber Teacher, I want you to go by it and not what I think is correct.

Items like Radios or Light Bulbs are rated in WATTS.  Did you ever noticed that ?  Why, Why, WHY! ?

These devices are rated in WATTS to show how much power they consume at their maximum tolerance.  A 60WATT light bulb operates at 60WATTS, which would be it's ideal power input.  If you feed it too much WATTAGE or POWER, you will blow the bulb.  Same thing with speakers and radios.  They are rated by their maximum WATTAGE capability.  1WATT speaker can operate at lower wattage, but if you exceed 1 WATT you are playing with fire and you will blow it if you pass it's tolerance.

Basically WATT is the unit of measurement of power.  WATT-HOUR is the unit of energy measurement equal to one WATT per hour.  A WATT-HOUR METER is a device that indicates instantaneous rate of power consumption of device or circuit.  You have one of those meters in your home and the electric company reads off of that.  To be more precise that is called a WATTMETER.

To figure out the circuits power at any given time of stable operation, and by that I mean, the VOLTS and AMPS are not moving in and out like crazy, simply multiply AMPS x VOLTS and you get = WATTS.

1 Horse Power = 746 WATTS, so if the circuit is operating at 460 VOLTS and uses 16 AMPS, it's power of consumption at that moment is  ? 7360 WATTS.  To get HP, simply divide 7360/746 to get approx. 9.8 HP, cool!

How many Volts and AMPS does a 1 WATT hand help CB (walkie talkie) radio use ? 1 VOLT and 1 AMP ?

Ummm, no.  You can clearly see that it is using batteries that are of a little higher value then 1 VOLT, but the AMPS are less then 1 AMPS, much less then that.

I am purely guessing now, 9V and to get 1 WATT I would say it would have to be, about 0.11 AMP, because 0.11 x 9 = 1 WATT, makes sense.

Now when making the I, E, R equations, you must make sure that you use the same basic units: E in Volts, I in amperes and R in Ohms.  You also have to remember about smaller or bigger values.  What do I mean ?

Some bigger resistors are so big that it would be incorrect to use OHMS because of their high ratings, so we use kilohms or milliamperes in AMPS for smaller ratings.  These must be changed to the basic units.  This means that you will most likely have a decimal point to deal with, but that is necessary to get the right answer.  Using KILO saves spaces when dealing with math.

100 milliamperes is not 100 AMPS, it is .10 AMPS.  There is 1000 milliamperes to 1 AMP   Similarly, 3.5 Kilohms is not 3.5 OHMS it is 3.5 to the 10(3) power or 3.5 times 1,000 = 3,500 OHMS.

So a circuit with a resistance of 3.5 Kilohms and with a current of 100 milliamperes would have a voltage of what ?

350 VOLTS of Potential Force, this is HIGH VOLTAGE!  If you touch it, you will most likely die or be seriously injured.

Pico - one millionth of one millionth of basic unit  /  Pico = x 10(-12)
Micro - one millionth of basic unit  /  Micro = x 10(-6)
Milli - one thousandth of basic unit  /  Milli = x 10(-3)

( anything above this line is smaller then basic unit )
Basic UNIT -------------------------------------------------------
( anything below this line is larger then basic unit )

Kilo - one thousand times basic unit  /  Kilo = x 10(3)
Mega - one million times basic unit  /  Mega = x 10(6)

Everything in the ( ) is a power of ten.  (  ) with a negative sign like this (-11) are negative powers of ten.

Think of it like this.  Draw a straight line on a plain piece of paper.  Find the middle, mark it with a point and name that 0, just like in math.  Everything to the left is negative -0, everything to the right is positive +0.

0 is the basic unit of measure.  Kilo is the first larger then basic unit of measure and then we use MEGA for even larger values when it becomes impractical to use KILO.  And these two would be to the right side as + or bigger numbers.

Milli would be the first on the - negative side or smaller then basic unit of measure, then Micro and Pico.

Series Circuits

When you have two or more components in a circuit connected end to end, this is called a Series Circuit connection.  In this type of a component connection, the current of electricity flows through each component.

If you had for example 3 resistors connected in SERIES they would be identified on a schematical drawing with little numbers besides them to identify one from the other.  Like: R1, R2, R3, that is Resistor Number 1 and 2 and 3 and so on.

E = 10 VOLTS    -  | ------> R1 (300 OHM) ------> R2 (200 OHM) ------> R3 (100 OHM) ------> |  +

What is the CURRENT in this Circuit ?

---> indicates electron flow, or polarity.  R with a T, like this:   RT is simply a way of writing the total resistance of all three of these resistors R1 through R3.  The RT here would be 600OHM TOTAL.

Simply  I = E/R   We know that E = 10 and RT = 600  so  10/600 = 0.01666 AMPS or 16.66 milliamps

How do you find the total circuit current if a series circuit has 3 resistors and each of them is of different value ?

( note on the picture I = 0.01 and not 0.10, will have to correct that later )

First you total all the resistances for all three resistors, 500 + 500 + 1000 = 2000OHM, so RT = 2,000OHM

Then you use the equation from above as I mentioned, we have R  and E, so we are missing I.  Then we solve for I and we pick I on the left side of the equal sign or like this I = E/R or 0.01APM = 20/2000, or 0.01APMS or 10 milliamperes
.
20 volts  E or Volts
--------- divided by
2000 ohm  R or Resistance

= 0.01 AMP  I

There is much more to series circuits then what I mentioned here, please go to the LIBRARY and borrow a book or buy one.  The best place to go for electrical books is to college stores.  You do not have to be a student to buy them, just show some money and they will sell them to you.

Go into the electrical section.  Or if you have lots of time and money, or maybe your parents are rich or have saved for your education since your beginning, go to a technical college for electronics.  You will not! learn much about electronics if you just go for regular college courses, you are wasting your time and your parents money.  Or borrow from a bank :- ) happy learning, they will lend to you, and you don't even have to have any credit at all.

PARALLEL Circuits, MHOS and SIEMENS coming up.

In a parallel circuit, components are connected side by side and they also provide multiple paths for the current to flow through.  If sometimes you see on a skematical drawing this  right by the battery drawing < ES = 20 V > instead of just E which stands for VOLTS that simply means, Voltage source, the S stands for source.

This is going to sound strange but in parallel circuits the current will increase as you add more resistors in parallel.  Why ? Because each time you add another resistor, that resistor it's self provides another path for the current to flow and the total current increases.

If you have two equal resistors of let's say 200 OHMS connected in the above circuit then the total circuit resistance may be found by this formula.  This formula by the way can be used on any two or more resistors that are of same value.

( the value must be same of all these resistors for this to be correct )

RT = R / N, that mean Resistance Total equals = Resistor value divided by the number of resistors.

R = the value of any single resistor and N = the number of resistors in parallel.

So RT = 200OHMS / 2 = 100OHMS, then you simply find the voltage that is used by the circuit at any stable time of operation that you want this calculated for, let's say the above circuit uses 90 Volts, then you simply divide the volts by the 100ohms, like this 90/100 = 0.9 amps

To prove this you can simply divide 90 volts by each of the resistor's value 90/200 = 0.45 and then add the two together.

Power or WATTAGE can be found by multiplying AMPS x VOLTS or by multiplying OHMS or resistance by AMPS squared like this R x I(2)

To find the resistance in a parallel circuit that has two or more unequal resistors here is what you do.

Rt = R1 x R2 and so on divided by / R1 + R2 and so on = OHMS or the answer that you are seeking.

IMPORTANT:  The total resistance of any parallel circuit MUST BE LESS THAN the value of any simple resistor in the parallel circuit.  Use this statement to check your mathematics when working with problems.

So let's say the two unequal resistors are 100OHM and 200OHM

100 x 200 / 100 + 200 = 20000 / 300 = 66.66666 ohms :- )

Now here is something NEW! Hooray!

CONDUCTANCE

The ability to conduct is opposite to the ability to resist.  Either may be used in the computation of circuit values.

Conductance of a circuit has been given the letter of G, as E is VOLTS and I is AMPS and R = OHMS.

So G = Conductance.

Conductance is measured in MHOS and if you look closely at this, MHOS is reverse of OHMS, only the S stays the same at the end of the word, basically OHMS spelled backwards.

The word SIEMENS is another term that you can use for MHOS.  MHOS or SIEMENS, same thing.

G is exactly reverse of R, so if Ohm's law says that R = E/I, then G = I/E which makes some kind of sense.

Conductance is really good to know about as it is later used in studies of transistors circuit parameters (controlling elements of a circuit such as voltage, current, resistance, inductance and capacitance). 

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