Permanent Magnet & Electromagnet Principles

Outline Permanent Magnets Electromagnets 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 Iron, Nickel, Cobalt and Gadolinium Uses Fridge 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 Force Like Poles want to repel each other S N N S Magnetic fields collide and push against each other

Attracting Force Differing poles tend to be attracted to each other

Pith Balls

Metal Leaf Electroscope To detect current…

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 Stronger 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 five foctors: Number of turns/loops Current through the coil Permeability of the core material Wire material type Size/gauge of the wire

1. Number of turns in the coil The more turns in a coil, the stronger the magnet The less turns the weaker the magnet

2. Amount of current in the coil - If the voltage is increased, so will the current,which will increase the strength of the magnetic field - If the voltage is decreased the strength of the magnetic field will decrease.

3. Permeability of the core material - Permeability: The ability of a material to be magnetized, even temporarily, and to transmit magnetic force - Air or glass would make a weak magnet - Silver or iron would make a strong magnet

4. Wire Material Type Although, metal wires are very efficient conductors of electricity, they still have some resistance to the flow of current depending on the make of the metal. Pure metals over alloys. Silver, copper, gold., aluminum, zinc, nickel, brass, bronze are excellent conductors. Stronger magnets. Mercury, lead, alloys of iron and chromium, titanium and stainless steel are poor conductors of . Weaker magnets

5. Wire Size/Thickness/Gauge Larger gauges of wire on the coil will decrease resistance. This will increase the current and therefore the field and the strength of the magnet. Using smaller gauges will increase the resistance, reduce the current and weaken the field and weaken the 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 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 five things determine an electromagnet’s strength? Number of turns/loops Current through the coil Permeability of the core material Wire material type Size/gauge of the wire