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.

7
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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.

10
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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.

15
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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.

20
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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.

22
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