Electricity,Magnetism, and Motion 

When a wire with a current is placed in a magnetic field, electrical energy is transformed into mechanical energy.

. A magnet can move a wire with a current. The magnetic field of the magnet interacts with the magnetic field of the wire with a current. The result is that the wire moves. 

.The ability to move an object is called energy. The energy of electric currents is called electrical energy.

.Electrical energy changes into mechanical energy when a wire with a current is placed in a magnetic field. The electrical energy produces the magnetic field in the wire with a current. The movement that results is mechanical energy.

Galvanometers

An electric current is used to turn the pointer of a galvanometer.

.A galvanometer is a device that measures small currents.

.A galvanometer contains an electromagnet. The electromagnet is between the opposite poles of two permanent magnets

.A current in the electromagnet produces a magnetic field. The electromagnet's magnetic field interacts with the magnetic fields of the permanent magnets. This interaction causes the electromagnet to move.

.A pointer is attached to the electromagnet in a galvanometer. When the electromagnet moves, the pointer moves. A scale shows how much the pointer moves. The current through the electromagnet is measured on the scale.

Electric Motors

An electric motor transforms electrical energy into mechanical energy.

.An electric motor uses an electric current to turn an axle. An axle is a rod. For example, an electric motor turns the axle of a fan. The fan blades are connected to the turning axle.

.An electric motor works by changing electrical energy into mechanical energy.

.In an electric motor, a loop of wire spins continuously. IT spins continuously by changing the direction of the current at each half turn of the loop. Every half turn of the axle, the current reverses. First it goes one way, and then it goes the opposite way.

.The part of an electric motor that reverses the current is called a commutator. A commutator is a ring split in half.

Induction of Electric Current

An electric current is induced in a conductor when the conductor moves through a magnetic field. 

. Motion can produce electrical energy. Suppose you move a conductor, such as a wire, through a magnetic field. By doing this, you will create an electrical current in the conductor.

.Electromagnetic induction is when an electric current is created in a conductor by moving the conductor through a magnetic field. This is called "inducing a current" Current that is made by moving a conductor through a magnetic field is called induced current. 

.You can induce a current in two ways:

1. You can move the conductor through the magnetic field. 

2. You can move a magnet through a coil of wire.

> An induced current may flow in only one direction. A current that flows in only one direction is called direct current. Direct current is also called DC.

.An induced current may reverse directions very quickly over and over again. A current that reverses direction repeatedly is called alternating current. Alternating current is also called AC

Generators

A generator uses motion in a magnetic field to produce an electric current.

. An electric generator changes mechanical energy into electrical energy.

. An electric generator is the opposite of an electric motor. Remember, an electric motor changes electrical energy into mechanical energy.

.Some generators produce alternating current. They are called AC generators.

.Some generators produce direct current. They are called DC generators.

.The electric company uses giant generators to produce electrical energy for your home and school.

Transformers

a transformer is a device that increases or decreases voltage.

.Electric companies send electrical energy through wires at high voltages. Your home, though, uses electrical energy at low voltages. Transformers are used to change the voltages of an electric current.

.A transformer is made up of tow coils of wires, each wrapped around an iron core.

.One coil of  transformer-called the primary coil -is connected to an alternating current. The other coil-called the secondary coil-is not connected to a source of electricity.

.Alternating current flows through the primary coil of a transformer. This causes a magnetic field to change as the current alternates. The changing magnetic field induces a current in the secondary coil.

. A transformer can either increases voltage or decree voltage. A step-up transformer increases voltage. In a step-up transformer, there are more loops in the secondary coil than in the primary coil.

.A sep-down transformer decreases voltage. In a step-down transformer, there are fewer loops in the secondary coil than in the primary coil.

.Transformers allow safe transfer of electrical energy from generating plants to homes and other buildings.