Transcript Permanent Magnet & Electromagnet Principles

Permanent Magnet &
Electromagnet Principles
Electricity/Electronics
Technology Department
Rondout Valley High School
Outline

Permanent Magnets
–
–
–
–

Poles
Magnetic Fields
Characteristics of Fields
Uses
Electromagnets
– How they are created
– Magnetic fields
– Uses
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 currentcarrying body in which magnetic forces
are observable
Permanent Magnet
S
N
Repelling Forces

S
Like Poles want to repel each other
N
N
Magnetic fields collide and
push against each other
S
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
Magnets that hold their magnetic forces
and can not be controlled are
called__________.
1.
•
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