magnets magnet activity #1 what will move a magnet? test the items listed below to see if they can...
Post on 30-Dec-2015
221 Views
Preview:
TRANSCRIPT
Magnets
Magnet Activity #1
What will move a magnet? Test the items listed below to see if they can make the magnet move. The next slide will reveal the answers.
ButtonNickel
Nuts & BoltsScissorsMarblePennyPaper ClipPencil
NoYesItem
What will make a magnet move?
Button
Nickel
Nuts & Bolts
Scissors
Marble
Penny
Paper Clip
Pencil
NoYesItem
Paper clips
attract...
because they are made of
iron.
Scissors attract.
because they are made of
iron.
Nuts and bolts attract.
because they are made of
iron.
Magnets in my house
Refrigerator magnets
Headphones
Telephone receivers Phone ringers
Seal around refrigerator door
Credit card magnetic strip
Computer monitor, hard drive, speakers
Shower curtain weights
Power supply transformersTV deflection coil
Microwave tubes
• Caused by electron spin
• An object in which all domains are aligned in the same direction
• Composed of ferromagnetic material (iron, nickel, cobalt, gadoliniuim).
What is a magnet?
What are magnetic domains?Magnetic substances like iron, cobalt, and nickel are composed of small areas where the groups of atoms are aligned like the poles of a magnet. These regions are called domains. All of the domains of a magnetic substance tend to align themselves in the same direction when placed in a magnetic field. These domains are typically composed of billions of atoms.
Magnetized ObjectsUnmagnetized Magnetized
For every North, there is a SouthIf you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole.
S N S N S N
No Monopoles Allowed - It has not been shown to be possible to end up with a single North pole or a single South pole, which is a monopole
S N
a material that is easily magnetized and
loses its magnetism quickly
Temporary Temporary MagnetMagnet
VS Permanent Permanent MagnetMagnet
materials that are hard to magnetize and
will also stay magnetized for a long
time
Magnetic Field LinesMagnetic field lines can be drawn in the direction a
north pole of a compass needle would point if placed at that point. The number of lines per area
show the strength of the field at that point.
Uses of magnets
• Magnets were first put to use in navigation because they always point north and south.
• Magnets are used to hold, separate, control, convey and elevate products and to convert electrical energy into mechanical energy or convert mechanical energy into electrical energy.
Ways to demagnetize a magnet
1.) Strike the magnet with force
2.) Heat it
The earth is like a giant magnet!
The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet.
We use the Earth’s magnetic field to find direction.
The needle of a compass always points toward the magnetic south pole.
We call this direction “North” (remember, opposites attract)
Activities #2 - #4
Supplement – What is in your breakfast
Electricity and Magnetism – how are they related?
1.) When an electric current passes through a wire a magnetic field is formed.
2.) when a wire is moved across a magnetic field, an electric current is induced in the wire
Demos & Activities
Magnet from electricity
• ELECTROMAGNET
Electricity from magnets
• ELECTRICAL INDUCTION
See Activity #4
In general, who has a better sense of direction?
1. Males
2. Females
Fun FactHumans have a small number of very tiny iron filings in the bone and cartilage of the nose, right in the center near the eyes. There is evidence that people can use these filings to orient themselves toward magnetic north even when blindfolded. MALES tend to have more of these filings, which explains why males tend to be better at geographic orientation (and why females tend to rely more on street names and other identifiable features).
http://www.youtube.com/watch?v=wOv0AkphLhE
Fun with Magnets
top related