magnetism. observe: snsn attract or repel? observe: snsn attract or repel?
TRANSCRIPT
Magnetism
Observe:
SN SN
Attract or repel?
Observe:
S N SN
Attract or repel?
Observe:
S N
SN
Attract or repel?
Observe:
SN
SN
Attract or repel?
Observe:
SN
SN
Make a map of the magnetic field around the
bar magnet
N S
Make a map of the magnetic field around the horseshoe magnet
Try this.
Try this.
What does the current in the wire do?
The magnetic field, B
N SB
A current makes a magnetic field
I
B
A current makes a magnetic field
I
B
I
BThis is called the right hand rule
Fields
• If you put a ______ in a __________ field, it will experience a force.
Fields
• If you put a ______ in a __________ field, it will experience a force.
• If you put a mass in a gravitational field, it will experience a force.
Fields
• If you put a ______ in a __________ field, it will experience a force.
• If you put a mass in a gravitational field, it will experience a force.
• If you put a charge in an electrical field, it will experience a force.
Fields
• If you put a ______ in a __________ field, it will experience a force.
• If you put a mass in a gravitational field, it will experience a force.
• If you put a charge in an electrical field, it will experience a force.
• If you put a magnet in a magnetic field, it will experience a force.
Oddly enough…
Electrical and magnetic fields can attract and repel.
Gravitational fields seem to only attract
The relationship between electricity and magnetism
A moving charge affects a magnet
A moving magnet affects a charge
The relationship between electricity and magnetism
A moving charge affects a magnet… it makes a magnetic field
A moving magnet affects a charge… it makes an electrical field
The relationship between electricity and magnetism
A moving charge affects a magnet… it makes a magnetic field
A moving magnet affects a charge… it makes an electrical field
There is an application of the right hand rule for each of these
The relationship between electricity and magnetism
A stable magnetic field affects a charge…
A stable electrical field affects a magnet…
The relationship between electricity and magnetism
A stable magnetic field affects a charge…… only if the charge is moving
A stable electrical field affects a magnet… …only if the magnet is moving
The relationship between electricity and magnetism
A stable magnetic field affects a charge…… only if the charge is moving
A stable electrical field affects a magnet… …only if the magnet is moving
There is an application of the right hand rule for each of these
Electromagnets
• A coil of wire, carrying a current makes a magnetic field.
• If you put the coil around a piece of iron or steel, it becomes an electromagnet.
Electromagnets
• A coil of wire, carrying a current makes a magnetic field.
• If you put the coil around a piece of iron or steel, it becomes an electromagnet.
Where could you use an
electromagnet?
Solenoid
If a magnet can move into and out of the coil, it is called a solenoid.
Solenoid
If a magnet can move into and out of the coil, it is called a solenoid.
Where could you use a solenoid?
Electric motors
• An electric motor converts electrical energy into work, usually rotational motion.
• Usually, a magnet makes coil of wire rotate when a current is flowing.
Which direction is the force on the wire?
Which direction is the force on the wire?
Use the right hand rule !
B = the magnetic field =index finger
I = the (+) current=thumb
F = force on the wire =palm
B = the magnetic field =index finger
I = the (+) current=thumb
F = force on the wire =palm
What is the missing vector ?
I
B
What is the missing vector ?
I
B
Motors--Convert electrical energy into mechanical energy--An electric current causes a coil of wire to spin in a magnetic field--The rotational motion can do many jobs
Mechanical Energy Electrical Energy
Generators--Convert mechanical energy into electrical energy--A coil of wire spinning in a magnetic field causes an electric current--There are many ways to spin the generator
Mechanical Energy Electrical Energy
Motors--Convert electrical energy into mechanical energy--An electric current causes a coil of wire to spin in a magnetic field--The rotational motion can do many jobs
Generators--Convert mechanical energy into electrical energy--A coil of wire spinning in a magnetic field causes an electric current--There are many ways to spin the generator
Mechanical Energy Electrical Energy
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Generator: If you move the wire, the force is exerted on the charge
Motor: If you move the charge (a current), the force is exerted on the wire
B B
I
Force EMF
Mechanical Energy Electrical Energy
B = the magnetic field =index finger
v = velocity of moving wire
=thumb
EMF = force on the charge =palm
What is the missing vector ?
v
B
What is the missing vector ?
v
B
What is the missing vector ?
v
EMF