Download Manetism and Electricity

Magnetism and Electricity (6-5.3)
-interpret diagrams of electromagnets, generators, or electric motors showing how electricity and magnetism are interrelated;
-summarize information about how electricity and magnetism are interrelated using diagrams, models, and descriptions of devices;
-compare devices based on how they interrelate electricity and magnetism;
-recognize devices based on their functions.
Magnetism
Magnetism: the force (push or pull) of attraction or repulsion of magnetic materials
Magnet:
-any material that produces a
magnetic field
-has atoms that align to two
ends (north and south)
Magnetic Behavior:
- Opposite (different) poles
attract or pull each other
(attraction)
- Like (same) poles repel or push
each other away (repulsion)
- If you cut a magnet in half: the
north and south poles will still exist on either end
Magnetic Field:
- Surrounds a magnet
- Applies a force (a push or pull), without actually touching
an object (invisible)
Electric Current- can be formed from either:
- a coil of wire spinning around a
magnet
- a magnet spinning around a coil of
wire
Earth’s Magnetic Field
(created from a moving
liquid iron and nickel core)
Bar Magnet
Magnetism and electricity are interrelated, which means that they can often be connected
This relationship can be demonstrated by the following devices: 1. Electromagnets 2. Generators 3. Simple electric motors
Electromagnets
An electromagnet is formed when: a wire in an electric circuit is wrapped around an iron core which produces a
magnetic field.
An electromagnet can be turned on or off.
- It only acts like a magnet when electric current is flowing
-
The magnet that is made loses its magnetism if the electric current stops
flowing.
Electromagnets are different from regular magnets because electromagnets:
- Can be turned on and off
- Can reverse polarity (North and South poles) which changes the direction of
the current
- Their strength can be controlled
Electromagnets (continued)
_______  _________
Transformation:
- The magnetic field of an electromagnet can be
made stronger by:
- Coiling a wire
- Adding more electric current
- increasing the size of the iron core (nail)
- An electromagnet can be made from a nail, wire, and a battery (stored CE)
-Some uses of electromagnets: magnetic locks, MRI machine, loudspeakers, headphones,
and motors.
Generators
_____  ______
Generators produce an electric current when a coil of wire wrapped around an iron core is rotated near a magnet
Generators at power plants
- produce electric energy for our homes.
- transform mechanical energy (ME)  electrical energy (EE)
A generator contains:
- coils of wire that are stationary
_____→ _____
- rotating magnets that are moved by turbines.
Turbines are huge wheels that rotate when pushed by
water, wind, or steam.
Sometimes generators have stationary magnets and coils
that rotate.
The magnet moving inside a coil of wire produces an
electric current.
- pulls electrons and sends them down the wire,
causing the electric charge
Small generators can be powered by gasoline
Simple Electric Motors
_____  _______
Contain an electromagnet that rotates between the poles of a magnet.
- The coil of the electromagnet is connected to a battery or other source of electric
current.
- When an electric current flows through the wire in the electromagnet, a magnetic
field is produced in the coil.
An electric motor changes electrical energy (EE)  to mechanical energy (ME).
Coil rotates because like poles of the magnets repel and unlike poles attract.
This rotating coil of wire can be attached to a shaft and a blade in an electric
fan, wheels, or anything that needs to rotate.
_____→ _____
Checking for Understanding
1. On magnets, like poles _________________________ and opposite poles
____________________________.
2. A magnet is surrounded by an invisible ___________________________________________________.
3. Spinning coils and magnets form a(n) ______________________________________________.
4. What are aligned inside a magnet that give it a north and a south end? ___________________
5. Which of the following metals can be magnetized? A. lead B. iron C. copper D. silver
6. Why are the magnetic domains of this paperclip lined up?
A. Because the paperclip has acquired a static charge.
B. Because a paperclip is a type of electromagnet.
C. Because paperclips are permanent magnets.
D. Because the paperclip has been exposed to a magnetic field
7. How can you create a magnetic field?
A. By stringing many magnets together.
C. By rubbing a piece of glass against a piece of wool.
B. By plugging a refrigerator magnet into an electric socket. D. By running a current through a wire.
8. Which of the following statements is true?
A. A compass is affected by the earth’s magnetic field.
B. An object’s magnetic field gets weaker as your move closer to it.
C. Once a piece of metal becomes magnetized, it stays magnetized.
D. The earth’s magnetic north pole is located at the geographical north pole
9. If you have an electromagnet, how can you make its magnetic field stronger?
A. Increase the size of the magnetic domains.
B. Increase the strength of the electrical current.
C. Increase the length of the wire.
D. Increase the distance between the north and south poles.
10. Match the device name to the simplified explanation
Device
Simple Explanation
Iron core + wire + electric current = magnetic field
Iron core + wire + magnet + rotation (movement) = electric
current
Electromagnet + electric current + magnetic poles = rotation
(movement)
11. Which device requires two magnets that attract and repel each other?__________________________
12. An electromagnet produces a ________________________ when electricity is added to a wire-wrapped piece of iron.
13. What 3 changes can increase the magnetic field of an electromagnet?
14. To change the polarity of an electromagnet, you would __.
A. Reverse the current’s direction
C. Turn the battery, or other power source, upside-down
B. Reverse the direction in which the coil is wound D. Remove the iron core from within the coil of wire
15. Which object can a student move through a coil of copper wire to produce an electric current in the wire?
A. battery B. magnet C. steel rod D. litmus paper