Jag Mark Name 3 different voltage sources.

Electricity, Magnetism, and Motion Notes

Electric Current and Magnetism Wherever there is electricity, there is magnetism. An electric current produces a magnetic field. This relationship between electricity and magnetism is known as electromagnetism.

Solenoids The magnetic field produced by a current can change in 3 ways: On/Off Direction Strength (add loops to the coil)

Solenoids A coil of wire with a current is called a solenoid.

Electromagnets A solenoid with a ferromagnetic core (Iron-magnet) is called an electromagnet. The overall magnetic field of an electromagnet can be hundreds or thousands of times stronger than the magnetic field produced by the current alone. An electromagnet is a strong magnet that can be turned on or off.

Electrical Energy and Motion 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.

Electrical Energy and Motion The ability to move an object is called energy. The energy of electric currents is called electrical energy. The energy of motion is called mechanical 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 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.

Galvanometers A current in the EM produces a magnetic field. The EM’s magnetic field interacts with the magnetic fields of the permanent magnets. This interaction causes the EM to move. A pointer is attached to the EM in a galvanometer. When the EM moves, the pointer moves. A scale shoes how much the pointer moves. The current through the EM is measured on the scale.

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

Electric Motors The name for the wire (or wire loops) that contains the current and rotates is known as the armature.

Electric Motors

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 for 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.

Electric Motors As the commutator rotates with the armature, it slides past two contact points called brushes. Each half of the commutator is connected to the current source by one of the brushes. As the armature rotates, each part of the commutator contacts one brush, then the other. Because the brushes conduct the current, changing brushes reverses the direction of the current in the armature. The reversing of the direction of the current causes the armature to spin continuously.