Permanent Magnet & Electromagnet Principles Electricity/Electronics Yvonne Brannum

Outline Permanent Magnets Poles Magnetic Fields Characteristics of Fields Uses Electromagnets How they are created Magnetic fields

Permanent Magnets Holds a magnetic force Can not be turned on and off Uses Frig Magnet Speakers Electric Motors Many more….

Magnetic Poles Refers to the ends of a permanent magnet, either North or South Determined by its charge (placement of electrons) Permanent Magnet S N

Magnetic field: The region around a magnet or current-carrying body in which magnetic forces are observable Permanent Magnet S N

Repelling Forces S N N S Like Poles want to repel each other Magnetic fields collide and push against each other

Electromagnets Use electricity to create a magnetic field They can be controlled (turned on and off) Their force or strength of field can be controlled

Electromagnet Basics Current-Carrying Wire Needs to have electron flow Electromagnetic Field around a wire

Determining the Direction of the Magnetic field Left-Hand Rule: Grasp a wire with your left hand with your thumb pointing in the direction of current flow Your fingers around the wire point in the direction of the field

Creating a Larger Magnet Coils Each loop of coil has a small amount of magnetic pull When the loops are added together the coil begins to act as a magnet with poles

Electromagnetic Field

Strength of Electromagnets Depends on three main things: Number of turns in the coil The more turns in a coil, the stronger the magnet Amount of current in the coil If the voltage is increased, so will the current,which will increase the strength of the magnetic field

Strength of Electromagnets(cont.) Permeability of the core material Permeability: The ability of a material to be magnetized, even temporarily, and to transmit magnetic force Air would make a weak magnet Iron would make a strong magnet

Putting Electromagnets to Use Solenoid: Is an electromagnet with a moveable core called a plunger

Uses for a Solenoid Electrical Relays Buzzers Switches Locks Bells

Solenoid Uses

Other uses for Electromagnets Transformers Industry Sensors Motors

Summary 1. Magnets that hold their magnetic forces and can not be controlled are called__________. Permanent Magnets 2. Refers to the region around a magnet or current carrying device where magnet forces are observed. Magnetic Field

Summary (cont.) 3. How is the direction of a magnetic field determine around a current carrying wire? Left-Hand Rule 4. What three things determine an electromagnet’s strength? Number of turns Current through the coil Permeability of core material