Rudiments of Electronics
>>Course Overview:
By the end of this tutorial
,you will become familiar with the following topics and concepts.
NB: We won't go into details with the theory aspect..just try and understand the concepts and the laws ...with that you are good to go.
*What is Electronics
*Some examples of electronic components.
*Relationship between:
>>Voltage
>>Current
>>Resistance
*Ohm's Law.
Electronics
What is electronics? Whenever you hear the word electronics,what comes into your mind?For me, is like electrons are in play. Okay! So the word electronics is actually coined from the behaviour of electrons in atoms of matter.I hope you guys did elementary science or maybe physics.So the mere mention of atoms shouldn't scare you off.By definition atoms are the smallest particle of an element which can be combined with other atoms to form a molecule.
Okay let's break things down here for better understanding. Let's take a wood for example.The wood here is matter 'cos it occupies space and also has mass.
When we cut this wood into several pieces such that the smallest piece becomes invisible to the eye, (I know that sounds impossible right? But it's kind of possible in the micro world) ...that invisible piece of wood is the atom we are talking of.
To make things simpler, consider a very big mansion on the outskirt of a city.Now when we move closer to the mansion assuming there are no plastering and paintings on the wall, the individual bricks making up the building is similar to an atom.Hence we can say atoms are the basic building blocks of matter.Now I hope you know what an atom is.So what of an electron( our main focus in this course of tutorial).
An electron is a subatomic particle of an atom(it is located inside an atom)
An electron is having a negative charge of value -1.602×10^-19C with a symbol of (e).
NB:The symbol ^ means raised to the power.
The other subatomic particles are the proton and neutron with a positive and neutral (zero) charge respectively.
Now, our main aim here is to understand what electronics is all about.So coming back to electrons, we know that e=-1.602×10^-19 coulombs(C).Whenever there is an increase in the energy level of an electron, it becomes mobile.Meaning it moves from one energy level to another hence causing the flow of electric current.So electronics basically is just the study of the behaviour of electrons in atoms of matter in order to control their flow in conductors and semiconductors as they move or transit from one energy level to the other. That brings us to another subtopic but we will learn about them (conductors,semiconductors and insulators) in electric circuits just for better understanding.
Electronic Components
Electronic components are the circuit elements used to control the flow of current in a circuit.
Examples of Electronic components:
Now that we know what electronics and electronic components are, let's take a look at the various electronic components used to control the flow of these electrons in a circuit.
1.Resistor
Resistor is used for limiting current in a circuit.It has a physical quantity called Resistance measured in ohms.
2.Diode
Diode is an electronic component used in a circuit for directing current on a single path.Diodes act like valves.
3.Light Emitting Diode(LED)
For producing light(photons) by passing current through them.The longer leg is the positive terminal and the short leg the negative terminal.It has a voltage drop of 0.6 to 0.7 volts(silicon diode) when operating at it's rated current.
4.Capacitor
The capacitor basically stores electrical charges.But it's also used in filtering current and others.It's physical quantity is the capacitance measured in farad.(smaller units = micro,pico, and nano farad).
NB:This is a basic introductory course so we are only going to deal with these few components for now.We will learn more about other advanced components but in project tutorials.
Relationship between Voltage, Current and Resistance
Voltage:Consider a ball at the top of a hill.The ball is then dropped downhill.
Most beginners find it very difficult to understand these three concepts so I will use some scenarios( like the one above) to make things clearer,easy and understandable.Now going back to the scenario above, we all know that the top of the hill is higher than the bottom.
As the ball rolled downhill gradually, the altitude also decreases accordingly till the ball reaches the bottom of the hill where it comes to a stop.
Now the ball initially was at a higher altitude, as it rolls down it losses it's altitude gradually till it reaches the bottom. So considering the two stationary points of the ball that is the top and the bottom.In maths we will say the top is greater than the bottom in terms of real values.But applying this concept to the voltage across a resistor, the top would be assigned a positive and the bottom a negative.The voltage concept here is the difference between the two points (potential difference).
So whenever there is a potential difference (p.d) between two points or nodes in a circuit, we call that a voltage.
Illustration example
In diagram A, point (a) is at a higher potential than point (b) because of the polarity of the voltage source(the driving force of the circuit).Since conventional current direction determines the potential difference (p.d) across a component, it follows that there's always a voltage drop across a resistor in this direction.(this applies in circuit analysis 'cos it reduces your chances
of error during calculations.I know this sounds crazy to you but it's always true when you work it out.
In diagram A, the conventional current direction is towards point (a) meaning point (a) is at a higher potential than point(b).Therefore as you move from a to b there would be a voltage drop hence the voltage across the resistor is +Vab.Huh! Why not - Vab 'cos +Vab=(Va-Vb)....which yields a positive result....since Va>Vb.
In diagram B, the conventional current direction is towards point(b).Meaning when we move from a to b ,there is a rise in voltage from negative (-) to positive(+).Hence the voltage across the resistor will be -Vab...'cos -Va-Vb=-Vab or +Vba when you change the direction and this is always true.
Definition and unit of voltage
Voltage Vab between two points a and b ,is the energy or work required to move a unit charge from point a to b , measured in volts(V).
Mathematically V∆(dw/dq).
V=w/q=J/C(volts)
where w= energy needed to move the charge,measured in joules(J).
and q= charge measured in coulomb (C).
Voltage or potential difference is the energy required to move a unit charge through an element measured in volts(V).
The potential at point (a) with respect to point (b) is Vab.
>>Vab=-Vba.
Example
NB: Voltage is always across an element or between two points in a circuit.
Current
Consider a flowing stream.The moving waves of the stream is quite similar to the current in circuit.When an electron carrying a charge passes through a point at a certain period of time, the current of electrons like the current of the waves in a stream through the circuit at that particular time, is the total amount of charge carried by the electrons passing through that particular point per unit time.To better understand this, let's take a piece of copper for example.
The copper atomically consists of electrons carrying negative charges.Now the amount or total number of electrons passing through a particular point A , times the net charge on the electrons per unit time is termed the current across the copper.
Mathematically, current (I)=(e×dn)/DT
where e=net charge on electrons
and dn=total number of electrons.
>>>q=e×dn
.
. . I=q/t where t = time measured in second.
Definition and Unit of Current
The electric current by definition is the is the time(t) rate of change of charge(q).
Or charge(q) per unit time(t).
>>I=q/t=C/s=A
1 ampere(A)=1 coulomb(C)/second (s)
Types of electric current
1.Direct Current (D.C)
An electric current is said to be a direct one if it's magnitude remains constant with respect o time.It's symbol is I.
2.Alternating Current (A.C)
An A.C is the one that changes direction periodically hence sinusoidal in nature.It's magnitude varies with time.It has the symbol i. The light bulbs in our homes uses alternating current.
NB: Electric current is always through an element or component.
When voltage or current is used for
conveyinxg information the common term given to it is called signal.
Resistance
Resistance is the opposition to the flow of electric current. Consider the water tap in our homes .When we want to fetch water we open the tap and water comes out.When closing it the amount of water coming out reduces to it's minimum flow till the tap is his completely closed.
Basically that's how resistance works.But in a circuit we use a resistor to limit the flow of electric current in the circuit.The unit of resistance is the oh
In tutorial three(3) we will learn how to calculate the resistance of a current limiting resistor in a circuit.
Ohm's Law
circuicmost every topic there is always a universal law, that governs how things are related concerning that topic.The ohm's law in this aspect shows the relationship between voltage, current and resistance in a circuit.So the law states that the voltage V, across a resistor is directly proportional to the current I flowing through the resistor.
That is V =Ik..............(1)
where k=Resistance(R)= constant of proportionality which varies with external conditions such as changes in temperature.
From eqn.(1), V= IR
also I =V/R and R=V/I .
Hence you can solve for any unknown using the equations above when given two known values.
By Edwin
+233544897559
An aspiring Engineer, Blogger and an affiliate Marketer.
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