Download Period 3

Science
RULES
Magnetism-Magnets
Kailey Toro, Megan Ly, Chad
Unrue, Michael Fairbanks
Items 1-5 on the packet
The Big Idea:
• A moving electric charge is
surrounded by a magnetic field.
Magnetic Poles
• Each Magnet has a
North and South
pole
• Like Poles repel;
Opposite poles
attract
• BOTH poles are
always present in
any magnet
Even when you break
magnets apart, they
create new North/South
poles. They can create
new poles even at the
microscopic level!
Magnetic Fields
• The direction of the magnetic field outside a
magnet is from the north to south pole
• When the lines are closer together, the field
strength is greater
• The magnetic field strength is greater at the
poles
• If we place another magnet or a small compass
anywhere in the field, it’s poles will tend to line
up with the magnetic field
Magnetic Fields
• A magnetic field is produced by the motion of
electric charges
Electric Charges Electric Forces Magnetic poles
Magnetic fields
• There are charges surrounding the magnet, and
when magnets get close together they create the
magnetic field
• Strong magnetic field conductors: Iron, Nickel,
Cobalt
How does a compass work??
• The magnetic field around a current carrying
conductor is showing by arranging compasses
around a wire
• The compass’ line up with the magnetic field
produced by the current, a pattern of concentric
circles about the wire.
• When the current reverses direction, the
compasses turn around, Showing the direction
of the magnetic field changes also.
Earth’s Magnetic Field
• A compass points northwards because earth
itself is one GIANT magnet.
• The needle in the compass aligns with the
magnetic field of the earth to point you in the
direction you need to know- however it DOES
NOT POINT TO TRUE NORTH
• The discrepancy is known as the magnetic
declination
Magnetic Field Reversals
• It’s been proved that Earth’s magnetic field is
not stable. The poles have flip flopped
throughout geological time
• Alternating magnetic strip of magnetized rock
show that there have been times when the
Earth’s magnetic field has dropped to zero and
then reversed
Magnetic Force Equation
• There is always a magnetic force!!!
• F=qvB
▫ q= amount of charge (C- for coulombs)
▫ v= velocity
▫ B= magnetic field ( T for teslas)
Right Hand Rule #1
• Point fingers in direction of moving charge (q)
• Orient your palm so it’s facing the direction of
the magnetic field (B)
• Extend your thumb, it’s the direction of the force
• This force happens only when the charge moves
perpendicular to the magnetic field B
Right Hand Rules #2
• To determine the direction of the circular
magnetic field around a wire carrying a current
• Direct your thumb along the wire in the
direction of current
• Your fingers curl in the direction of the circular
magnetic field
Magnetism Problems
1. A charged particle moving in a magnetic field experiences a deflecting force that is
maximum when the charge moves _________ to the field
A. Parallel
B. Next
C. Perpendicular
2. An electromagnet can be made from a current-carrying wire coiled around a piece of:
A. Iron
B. Copper
C. Tin
D. Any metal
3. Which pole of the bar magnet is facing North?
A or B?
Magnetism Problems
4. If you break a magnet in half…
A. It will lose its magnetic pull
B. Two smaller magnets will be formed
C. The phenomenon varies for every type of metal used to create the magnet
D. Each piece will only have one pole, not both
5. The space around a magnet, in which a magnetic force is exerted, is filled with a…
A. Magnetic domain
B. Iron fillings
C. Magnetic Field
D. nothing
6. In an electromagnet, the magnetic field intensity increases as the number of loops
A. Decrease
B. Increase
C. No change
7. Why aren’t most materials magnetic?
A. They don’t carry an electric charge
B. The electric fields of the domains cancel each other out because they aren’t aligned
C. Only metals can be magnetic
Magnetism Problems
8. Why don’t compasses point to the geographic North Pole.
A. Minor imperfections in the compass
B. Because of man-made magnets that are stronger than the earth’s
magnetic field
C. The magnetic North Pole doesn’t match the geographic North Pole
9. What causes magnetic fields?
A. Moving electric charges
B. Only magnetic objects can create magnets
C. Static electricity
10. A Tesla is a unit of measurement of what?
A. The force created by a magnetic field
B. The magnitude of a magnetic field
C. The electric charge of a magnet
Answers
1) C. Perpendicular
2) A. Iron
3) B
4) B. Two smaller magnets will be formed
5) C. Magnetic Field
6) B. Increase
7) B. The electric fields of the domains cancel each other out because
they aren’t aligned
8) C. The magnetic North Pole doesn’t match the geographic North Pole
9) A. Moving electric charges
10) B. The magnitude of a magnetic field