In a sense an electric motor is the opposite of an
electrical generator. If current flows through a wire that is in a
magnetic field (produced either by a permanent magnet or current flowing
through a coil), a mechanical force will be generated on the wire.
That force can do work. In a motor, the wire that moves through the
field and experiences the force is also in the form of a coil of wire,
connected mechanically to the shaft of the motor. This coil looks like
and acts like an inductor; if you turn off the current (to stop the
motor), the coil will still be moving through the magnetic field, and
the motor now looks like a generator and can produce a large voltage.
The resulting inductive voltage spike can damage components, such as the
circuit that controls the motor current.
Combinations of Inductors
You already know how inductors act in combination because they act
just like resistors. Inductance adds in series. This makes physical
sense because two coils of wire connected in series just looks like
a longer coil. Parallel connection reduces inductance because the
current is split between the several coils and the fields in each
are thus weaker.
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).
Voltage is something is a type of "pressure" that drives electrical
charges through a circuit.
charges attract, they exert a force on each other pulling them
together. The magnitude of the force is proportional to the product
of the charge on each mass.
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.
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.
What is Energy Star?
Home Electrical Wiring Types and Rules
Surface Mount Device (SMD) or Surface Mount Electronic Components
SMD Coil – Surface Mount Chip Coil Guide
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