Similarly, the voltage between two points A and B , VAB
, is relative. If VAB is positive you know the two points
are oppositely charged, but you cannot tell if point A has positive
charge and point B negative, or visa versa.
However, if you make a second measurement between A and another point C
, you can at least tell if B and C have the same charge by the relative
sign of the two voltages, VAB and VAC to your common point A .
You can even determine the voltage between B and C without measuring
it: VBC = VAC - VAB . This is the
advantage of defining a common point, like A , as ground and making
all voltage measurements with respect to it. If one further defines
the charge at point A to be negative charge, then a positive VAB
means point B is positively charged, by definition. The names and
the signs are all relative, and sometimes confusing if one forgets
what the reference or ground point is.
Fig - 2:
Like charges exert a repulsive
force on each other.
Learn More on Basics of Electronics:
the branch of
science that deals with the study of flow and control of
electrons (electricity) and the study of their behavior and
effects in vacuums, gases, and semiconductors, and with devices
using such electrons.
Rules of Electrical
* A voltage of 1V across a resistance
of 1 Ohm will cause a current flow of 1 Amp, and the resistor will
dissipate 1 Watt (all as heat).
is an electronic circuit?
A circuit is a structure that directs
and controls electric currents, presumably to perform some useful
function. The very name "circuit" implies that the structure is
closed, something like a loop.
Charge is mobile and can flow freely in certain
materials, called conductors. Metals and a few other elements and
compounds are conductors. Materials that charge cannot flow through
are called insulators. Air, glass, most plastics, and rubber are
insulators, for example. And then there are some materials called
semiconductors, that seemed to be good conductors sometimes but much
less so other times. Silicon and germanium are two such materials.
The flow of charge is called electrical current. Current is measured
in amperes (a), amps for short (named after another French scientist
who worked mostly with magnetic effects).
There are many different representations for basic
wiring symbols, and these are the most common. The conventions
I use for wires crossing and joining are marked with a star (*) -
the others are a small sample of those in common use, but are fairly
representative. Many can be worked out from their position in
the circuit diagram (schematic).
What is charge?
may be defined as the quantity of unbalanced electricity in a body
(either positive or negative) and construed as an excess or
deficiency of electrons.
Charge comes in two forms,
positive (+) , and negative charge ( - ) .
Charges can be separated by several means to produce
a voltage. A battery uses a chemical reaction to produce energy and
separate opposite sign charges onto its two terminals. As the charge is
drawn off by an external circuit, doing work and finally returning to
the opposite terminal, more chemicals in the battery react to restore
the charge difference and the voltage. The particular type of chemical
reaction used determines the voltage of the battery, but for most
commercial batteries the voltage is about 1.5 V per chemical section or
A Resistor is
an electrical device that resists the flow of
electrical current. It is a passive device used to
control, or impede the flow of, electric current in an
electric circuit by providing resistance, thereby developing
a drop in voltage across the device.
The value of a resistor is measured in ohms
and represented by the Greek letter capital omega. Resistors usually
have a brown cylindrical body with a wire lead on each end, and
colored bands that indicate the value of the resistor.
Ohm's law describes the relationship between
voltage, V , which is trying to force charge to flow, resistance, R
, which is resisting that flow, and the actual resulting current I .
the Electric energy produced per unit time.
In simple words, we can say that a capacitor is a device
used to store and release electricity, usually as the result
of a chemical action. Also referred to as a storage cell, a
secondary cell, a condenser or an accumulator. A Leyden Jar
was an early example of a capacitor.
An inductor is
an electrical device (typically a
conducting coil) that introduces inductance into a circuit.
An inductor is a passive electrical component designed to
provide inductance in a circuit. It is basically a coil of
wire wrapped around an iron core. simplest form an inductor
is made up of a coil of wire. The inductance measured in
henrys, is proportional to the number of turns of wire, the
wire loop diameter and the material or core the wire is
A conductor made with semiconducting
material. Semiconductors are made up of a substance with electrical
properties intermediate between a good conductor and a good
insulator. A semiconductor device conducts electricity poorly at
room temperature, but has increasing conductivity at higher
temperatures. Metalloids are usually good semiconductors.
Silicon, atomic number 14 on the periodic table, is a semiconducting
material from which integrated circuits (computer chips of all
types--processors, memory chips, etc.; CCDs; transistors; etc.) are
Silicon is one of the most common elements. Silicon is also the
semiconductor material out of which almost all modern transistors are
A Diode is
an electronic device that allows
current to flow in one direction only. It is a semiconductor that consists of a p-n junction. They are used
most commonly to convert AC to DC, because they pass the
positive part of the wave, and block the negative part of
the AC signal, or, if they are reversed, they pass only the
negative part and not the positive part.
Electronic Component name abbreviations:
Here is a list of Electronic Component name abbreviations
widely used in the electronics industry.
Current | Electric Current | AC (Alternate
Current) | DC (Direct Current)
Electronics and Electricity Basics
What is Energy Star?
Home Electrical Wiring Types and Rules
All about Semiconductor
Ball Grid Array (BGA) Package
SMD Surface Mount Electronic Components for SMT
How to Solder – Hand Soldering Tutorial
Printed Circuit Board: Design, Diagram and Assembly
Active and Passive Electronic Components
Electronic Components, Parts and Their Function
How Electronic / Electrical Circuit Works
How to Generate Electricity – How is Electricity Generated