BASIC ELECTRONICS - India’s Premier Educational · PDF fileWhat is Basic Electronics?...
Transcript of BASIC ELECTRONICS - India’s Premier Educational · PDF fileWhat is Basic Electronics?...
BASIC
ELECTRONICS
by
A.AsunthaA .P(O.G)
Department of ElESRM University
What is Basic Electronics?
Basic Electronics is a subject that deals with electronic component and its characteristics.
Types of Electronic component
1.Active component: components which produce the energy in the form of current or voltage are called as active components. Example:transistors
2.Passive Component :components which stores the energy in the form of current or voltage are called as passive components. Example: inductors,resistors,capacitors
Introduction
Water flowing through a hose is a goodway to imagine electricity Water is likeElectrons in a wire (flowing electronsare called Current)
Pressure is the force pushing waterthrough a hose – Voltage is the forcepushing electrons through a wire
Friction against the holes walls slowsthe flow of water – Resistance is animpediment that slows the flow ofelectrons
Types of current
Direct Current (DC)Flows in only one direction from negative toward positive pole of source
Alternating Current (AC)Flows back and forth because the poles of the source alternate between positive and negative
Concepts of conductors and insulators
Conductors and Insulators
There are some materials that electricity flows through easily. These materials are called conductors. Most conductors are metals.
Four good electrical conductors are gold, silver, aluminum and copper.
Insulators are materials that do not let electricity flow through them.
Four good insulators are glass, air, plastic, and porcelain.
Resistor
A resistor is a device whose function is to provide resistance
Resistance (R) is a measure of how much an object resists current for a specific potential difference across its two ends.
R = V/I
Resistance is measured in ohm.
Types of resistor
Fixed resistors come in a variety of different shapes, sizes and forms.
Axial lead resistors have the value of resistance printed on them or as a colour code
Surface mount resistors have a numerical code indicating a value
Types of resistor
Variable resistors are called potentiometers
There is a fixed value of resistance between two terminals
The moving part of the potentiometer is called the wiper
Resistor
Precision type resistor
Film type resistor
Variable type resistor
Colour coding of resistor
Four band resistor colour code
1st band provides the first digit of the code
2nd band provides the second digit of the code
3rd band is the multiplier
4th band indicates the tolerance value
Resistor colour codes
BLACK=0 GREEN = 5
BROWN=1 BLUE = 6
RED = 2 VIOLET = 7
ORANGE = 3 GREY = 8
YELLOW = 4 WHITE = 9
GOLD = 5 % SILVER = 10%
B B R O Y Great Britain Very Good Wife
Resistor value calculation
The first band red has a value of 2
The second band purple has a value of 7
The third band has a multiplier of x 10
The last band indicates a tolerance value of +/‐5%
Series and parallel resistor
A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. The current is the same through each resistor.The total resistance of the circuit is found by simply adding up the resistance values of the individual resistors
equivalent resistance of resistors in series R = R1 + R2 + R3 + ...
Parallel circuitA parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together. The current in a parallel circuit breaks up, with some flowing along each parallel branch and re‐combining when the branches meet again. The voltage across each resistor in parallel is the same. A parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together. The current in a parallel circuit breaks up, with some flowing along each parallel branch and re‐combining when the branches meet again. The voltage across each resistor in parallel is the same.
Inductor
An inductor is a coil of wire through which electrons move, and energy is stored in the resulting magnetic field
Inductors are simply coils of wire
(i)Can be air wound (just air in the middle of the coil)
(ii)Can be wound around a permeable material (material that concentrates magnetic fields)
(iii)Can be wound around a circular form (toroid
Inductor
Inductance is measured in Henry
A Henry is a measure of the intensity of the magnetic field that is produced
The amount of inductance is influenced by
1. Number of coil turns.
2. Diameter of coil.
3. Spacing between turns.
4. Size of the wire used.
5. Type of material inside the coil
Variables determining inductance
Capacitor
A device that stores energy in electric field.
Two conductive plates separated by a non conductive material.
Electrons accumulate on one plate forcing electrons away from the other plate leaving a net positive charge.
Think of a capacitor as very small, temporary storage battery
Capacitor
Capacitor identification
depends on the capacitor type.
Could be color bands, dots,
or numbers.
Variables determining capacitance
Energy band diagram
The range of energies that an electron may possess in an atom is known as the energy band.
Three Important energy bands are
•Valence Band•Conduction Band•Forbidden Band
Valence Band :‐The Range of Energy possessed by valence electrons isknown as valence Bands.
Conduction Band :‐
The valence electrons are less tightly bound with the nucleus. So that even an appication of small elctric field some of the valence electrons detached from the nucleus and it becomesfree electrons.
These fee elctrons are responsible for the conduction of currentin good conductors. The electrons are also called conduction electrons.
Forbidden Band (or) Energy Gap :‐
The energy band in between the condition band and the valence band is called forbidden Band.
Insulators
Conudctors
Semi conductors
Classification of Materials (or) Solids According to EnergyBands :‐
Solids are classified in to three types
Insulators :‐
→ The materials in which the condition band and valence bands are separeted by a wide energy gap (≈ 15 eV) as shown in figure.
→ A wide energy gap means that a large amount of energy isrequired, to free the electrons, by moving them from the valence band into the condition band ;
→ Since at room temperature, the valence electrons of an insulator do not have enough energy to jump in to the condition, therefore insulator do not have an ability to conduct current. Thusinsulators have very high resistively (or extremely low conductivity) atroom temperatures.
→ However if the temperature is raised, some of the valence electrons may acquire energy and jump in to the conduction band. It causes the resistively of insulators to decrease.
.
Conductors :‐
The materilas in which conduction and valence bands overlap as shown in figure are called conductors.
→ The overlapping indicates a large number of electrons available for conduction.
→ Hence the application of a small amount of voltage results a large amount of current.
Semiconductor
→ The materials, in which the conduction and valence bands are separeated by a small energy gap (1eV) as shown in figure are calledsemiconductors.
→ Silicon and germanium are the commonly used semiconductors.
→ A small energy gap means that a small amount of energy isrequired to free the elctrons by moving them from the valence band in to the conduction band.
→ The semiconductors behave like insulators at 0 K, because no electrons are available in the conduction band.
→ If the temperature is further increased, more valence elctrons willacquire energy to jump into the conduction band.
Thank you