# Electricity, Magnetism, and Motion - PowerPoint PPT Presentation

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## Electricity, Magnetism, and Motion

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### Notes Electric Current and Magnetism Wherever there is electricity, there is magnetism. An electric current produces a magnetic field. This relationship between ... – PowerPoint PPT presentation

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Title: Electricity, Magnetism, and Motion

1
Electricity, Magnetism, and Motion
• Notes

2
Electric Current and Magnetism
• Wherever there is electricity, there is
magnetism.
• An electric current produces a magnetic field.
• This relationship between electricity and
magnetism is known as electromagnetism.

3
Solenoids
• The magnetic field produced by a current can
change in 3 ways
• On/Off
• Direction
• Strength (add loops to the coil)

4
Solenoids
• A coil of wire with a current is called a
solenoid.

5
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6
Electromagnets
• A solenoid with a ferromagnetic core
(Iron-magnet) is called an electromagnet.
• The overall magnetic field of an electromagnet
can be hundreds or thousands of times stronger
than the magnetic field produced by the current
alone.
• An electromagnet is a strong magnet that can be
turned on or off.

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8
Electrical Energy and Motion
• A magnet can move a wire with a current. The
magnetic field of the magnet interacts with the
magnetic field of the wire with a current. The
result is that the wire moves.

9
Electrical Energy and Motion
• A magnet can move a wire with a current. The
magnetic field of the magnet interacts with the
magnetic field of the wire with a current. The
result is that the wire moves.

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11
Electrical Energy and Motion
• The ability to move an object is called energy.
The energy of electric currents is called
electrical energy.
• The energy of motion is called mechanical energy.
• Electrical energy changes into mechanical energy
when a wire with a current is placed in a
magnetic field. The electrical energy produces
the magnetic field in the wire with a current.
The movement that results is mechanical energy.

12
Galvanometers
• A galvanometer is a device that measures small
currents.
• A galvanometer contains an electromagnet. The
electromagnet is between the opposite poles of
two permanent magnets.

13
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14
Galvanometers
• A current in the EM produces a magnetic field.
The EMs magnetic field interacts with the
magnetic fields of the permanent magnets. This
interaction causes the EM to move.
• A pointer is attached to the EM in a
galvanometer. When the EM moves, the pointer
moves. A scale shows how much the pointer moves.
The current through the EM is measured on the
scale.

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16
Electric Motors
• An electric motor uses an electric current to
turn an axle. The axle is a rod. For example, an
electric motor turns the axle of a fan. The fan
blades are connected to the turning axle.

17
Electric Motors
• The name for the wire (or wire loops) that
contains the current and rotates is known as the
armature.

18
Electric Motors
19
Electric Motors
• An electric motor works by changing electrical
energy into mechanical energy.
• In an electric motor, a loop of wire spins
continuously. It spins continuously by changing
the direction for the current at each half turn
of the loop. Every half turn of the axle, the
current reverses. First it goes one way, and then
it goes the opposite way.
• The part of an electric motor that reverses the
current is called a commutator. A commutator is a
ring split in half.

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21
Electric Motors
• As the commutator rotates with the armature, it
slides past two contact points called brushes.
Each half of the commutator is connected to the
current source by one of the brushes.
• As the armature rotates, each part of the
commutator contacts one brush, then the other.
Because the brushes conduct the current, changing
brushes reverses the direction of the current in
the armature.
• The reversing of the direction of the current
causes the armature to spin continuously.

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