• An electromagnet is a type of magnet in which the magnetic
field is produced by the flow of electric current. The magnetic
field disappears when the current is turned off.
Electromagnets are widely used as components of other
electrical devices, such
as motors, generators, relays, loudspeakers, hard disks, MRI
machines, scientific instruments, and magnetic
separation equipment, as well as being employed as industrial
lifting electromagnets for picking up and moving heavy iron
objects like scrap iron.
• A dynamo is an electrical generator that
produces direct current with the use of
• The word dynamo (from the Greek word dynamis;
meaning power) was originally another name for
an electrical generator, and still has some regional
usage as a replacement for the word generator. A
small electrical generator built into the hub of a
bicycle wheel to power lights is called a hub
dynamo, although these are invariably AC devices
• A windmill is a machine that converts
the energy of wind into rotational energy by
means of vanes called sails. Originally,
windmills were developed for milling grain for
food production. In the course of history, the
windmill machinery was adapted to many
other industrial uses. An important nonmilling use is to pump water, either for land
drainage or to extract groundwater.
• Most hydroelectric power comes from the
potential energy of dammed water driving a
water turbine and generator.
• The turbine used here is attached to a dynamo.
• The power extracted from the water depends on
the volume and on the difference in height
between the source and the water's outflow.
• This height difference is called the head. The
amount of potential energy in water is
proportional to the head. A large pipe (the
"penstock") delivers water to the turbine.
• A hub dynamo is a small electrical generator built into the hub
of a bicycle wheel that is usually used to power lights. Most
modern hub dynamos are regulated to 3watts at 6 volts,
although some will drive up to 6 watts at 12 volts.
Nuclear power plant
• A nuclear reactor is a device to initiate and control a
sustained nuclear chain reaction.
• Nuclear reactors are used at nuclear power
plants for generating electricityand in propulsion of ships.
Heat from nuclear fission is passed to a working fluid (water
or gas), which runs through turbines.
• These either drive a ship's propellers or turn electrical
generators. Nuclear generated steam in principle can be used
for industrial process heat or for district heating. Some
reactors are used to produce isotopes
for medical and industrial use, or for production
of plutonium for weapons.
• Some are run only for research.