Transcript Magnets and Electricity

Magnetic Forces
In this activity you will:
• Learn about magnetism and electricity.
• Write a paragraph using three facts
about magnetism and three facts about
electricity.
What is magnetism?
• Magnetism is the force of attraction
between magnets and magnetic objects.
Characteristics of magnets
• Every magnet has two poles (North and
South)
• Every magnet has a magnetic field
around it.
– The magnetic field is lines of force running
from the north-seeking pole to the southseeking pole of the magnet
What do you know of that has
a North and South Pole?
• If you answered The Earth you were right!
• The Earth is one giant magnet. It has two
magnetic poles and is surrounded by a
magnetic field.
• This magnetic field is what causes the needle
of a compass to point in different directions
and causes the poles of a magnet to point
either north or south.
Do opposites attract?
• Yes!
• The north and south seeking poles of
two magnets attract each othermagnetic force pulls them together.
• But if you try to bring two of the same
poles (two norths or two souths)
together they will repel each other.
Magnets and electricity
• Magnets are used to generate, or
produce, electricity.
• Spinning a coil of wire inside a magnetic
field produces an electric force between
the ends of the coil.
• In a similar way, an electric current
produces a magnetic field around it.
Electromagnet
• A temporary magnet made by passing electric
current through a wire coiled around an iron
bar.
• A junkyard is one place to see an
electromagnet in action. A crane holding a
huge electromagnet can be used to pick up
scrap metal when current flows through it.
When the crane operator wants to drop the
scrap, he or she will simply shut off the current
to the electromagnet.
Ten Facts about Magnets
• 1. North poles point north, south poles
point south.
• 2. Like poles repel, unlike poles attract.
• 3. Magnetic forces attract only magnetic
materials.
• 4. Magnetic forces act at a distance.
• 5. While magnetized, temporary
magnets act like permanent magnets.
• 6. A coil of wire with an electric current
flowing through it becomes a magnet.
• 7. Putting iron inside a current-carrying coil
increases the strength of the electromagnet.
• 8. A changing magnetic field induces an electric
current in a conductor.
• 9. A charged particle experiences no magnetic
force when moving parallel to a magnetic
field, but when it is moving perpendicular to
the field it experiences a force perpendicular to
both the field and the direction of motion.
• 10. A current-carrying wire in a
perpendicular magnetic field experiences
a force in a direction perpendicular to
both the wire and the field
Writing Activity
• Write a paragraph about magnetism and
electricity including three facts about
each that you learned during this
presentation.