Science Chapter 8 Flashcards
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Questions and Answers

What is Magnetite?

  • A type of steel
  • A type of magnet
  • A geological formation
  • A mineral that attracts pieces of iron (correct)

    • How many years ago did Greeks discover deposits of a mineral that was a natural magnet?

    2000 years ago

    What does magnetism refer to?

    Properties and interactions of magnets

    What is a magnetic field?

    <p>Exerts a force on magnetic objects represented by field lines</p> Signup and view all the answers

    Where are the magnetic field lines the strongest?

    <p>At the poles</p> Signup and view all the answers

    Where is the magnetic force the greatest in a horseshoe magnet?

    <p>Near the poles</p> Signup and view all the answers

    What is theorized to cause the Earth's magnetic field?

    <p>Molten iron and nickel in Earth's core produce the Earth's magnetic field</p> Signup and view all the answers

    The north pole of one magnet will be attracted to the _____ of another magnet.

    <p>south pole</p> Signup and view all the answers

    Like magnetic poles always _____ each other.

    <p>repel</p> Signup and view all the answers

    Explain how a compass works.

    <p>A compass's needle is attracted to Earth's north pole and points to Earth's magnetic south pole. The needle rotates freely and its painted end represents the south magnetic pole, aligning itself with the magnetic field.</p> Signup and view all the answers

    Name three magnetic materials.

    <p>Nickel, Cobalt, and Iron</p> Signup and view all the answers

    What are magnetic domains?

    <p>Groups of atoms in magnetic materials that can align their magnetic poles</p> Signup and view all the answers

    What are temporary magnets?

    <p>Magnets that exist only when current is flowing through a wire</p> Signup and view all the answers

    What is a permanent magnet?

    <p>Material that is magnetized by placing it in a strong magnetic field</p> Signup and view all the answers

    Name two ways a magnet can lose its magnetic behavior.

    <p>Heating or striking with a hammer</p> Signup and view all the answers

    What does electric current create?

    <p>Magnetic fields</p> Signup and view all the answers

    What is an electromagnet?

    <p>A temporary magnet made by wrapping a wire coil carrying a current around an iron core</p> Signup and view all the answers

    What is a solenoid?

    <p>A wire wrapped into a coil</p> Signup and view all the answers

    How is magnetism lost in a coil?

    <p>By stopping or starting a current</p> Signup and view all the answers

    What are two ways to increase the magnetic force?

    <p>Increase the number of coils or increase the current</p> Signup and view all the answers

    How can you force an electromagnet to rotate?

    <p>With mechanical energy</p> Signup and view all the answers

    What is a galvanometer?

    <p>A device that uses an electromagnet to measure electric current</p> Signup and view all the answers

    What is an electric motor?

    <p>A machine that changes electrical energy to mechanical energy, used to do work</p> Signup and view all the answers

    Where is the voltage source on the motor?

    <p>Battery</p> Signup and view all the answers

    Where is the permanent magnet on the motor?

    <p>Magnet</p> Signup and view all the answers

    Where is the electromagnet on the motor?

    <p>Coil</p> Signup and view all the answers

    What is electromagnetic induction?

    <p>The process by which moving a wire through a magnetic field produces an electric current</p> Signup and view all the answers

    What is a generator?

    <p>A device that produces electric current by rotating a coil of wire in a magnetic field</p> Signup and view all the answers

    How does a generator work?

    <ol> <li>An electromagnet is placed between the poles of a permanent magnet. 2. The coil rotates by mechanical energy. 3. Electric current is produced as the coil turns through the magnetic field.</li> </ol> Signup and view all the answers

    What is alternating current?

    <p>When a current in a circuit reverses its direction in a regular pattern</p> Signup and view all the answers

    Give an example of alternating current.

    <p>Outlets</p> Signup and view all the answers

    What is direct current?

    <p>Current that flows in only one direction through a wire</p> Signup and view all the answers

    Give an example of direct current.

    <p>Battery</p> Signup and view all the answers

    What is a transformer?

    <p>A device used to increase or decrease the voltage of current in some motors</p> Signup and view all the answers

    What is a step-up transformer?

    <p>Increases voltage; second coil has more turns than the first coil</p> Signup and view all the answers

    What is a step-down transformer?

    <p>Decreases voltage; second coil has fewer turns of wire than the first coil</p> Signup and view all the answers

    What is a magnetic pole?

    <p>Region where a magnet's magnetic force is strongest</p> Signup and view all the answers

    What is a turbine?

    <p>A large wheel that rotates when pushed by steam, wind, or water, providing mechanical energy to a generator</p> Signup and view all the answers

    Study Notes

    Magnetite and Magnetism

    • Magnetite is a mineral capable of attracting iron.
    • Greeks discovered natural magnetic deposits approximately 2000 years ago.
    • Magnetism encompasses the properties and interactions of magnets.

    Magnetic Fields

    • Magnetic fields exert forces on magnetic objects, visualized as field lines.
    • Magnetic field strength peaks at the magnetic poles.
    • In a horseshoe magnet, the greatest magnetic force is also found near the poles.

    Earth's Magnetic Field

    • The Earth's magnetic field is theorized to result from molten iron and nickel in its core.

    Magnet Interactions

    • The north pole of one magnet attracts the south pole of another.
    • Like magnetic poles repel each other.

    Compasses and Navigation

    • A compass aligns itself with Earth's magnetic field, with its needle pointing north due to attraction between the needle's south pole and the Earth's magnetic north pole.

    Magnetic Materials

    • Key magnetic materials include nickel, cobalt, and iron.
    • Magnetic domains in materials can align to enhance magnetism.

    Types of Magnets

    • Temporary magnets exhibit magnetism only when current flows through a wire.
    • Permanent magnets are magnetized by exposure to strong magnetic fields.

    Losing Magnetism

    • Magnets can lose their magnetism through heating or physical impact, like hammering.

    Electromagnetism

    • Electric current generates magnetic fields.
    • An electromagnet is created by winding a current-carrying wire coil around an iron core.

    Solenoids

    • A solenoid is defined as a wire wrapped into a coil for generating magnetic fields.

    Electromagnet Behavior

    • Magnetism in a coil can be lost by stopping or starting the current.
    • Increasing the number of coils or the current itself can enhance magnetic force.

    Electromagnetic Applications

    • Mechanical energy can induce rotation in an electromagnet.
    • Galvanometers measure electric current using an electromagnet.

    Electric Motors

    • Electric motors convert electrical energy into mechanical energy for performing work.
    • A battery serves as the voltage source, while a magnet and coil represent the permanent magnet and electromagnet within the motor, respectively.

    Electromagnetic Induction

    • Electromagnetic induction refers to generating electric current by moving a wire through a magnetic field.
    • Generators operate by rotating a coil of wire within a magnetic field to produce electric current through mechanical energy.

    Current Types

    • Alternating current (AC) reverses its direction regularly, as seen in electrical outlets.
    • Direct current (DC) flows uniformly in one direction, typical of batteries.

    Transformers

    • Transformers adjust voltage levels in electrical circuits, with step-up transformers increasing voltage and step-down transformers decreasing it based on coil turns.

    Magnetic Poles and Turbines

    • Magnetic poles are areas where a magnet's force is most potent.
    • Turbines convert energy from steam, wind, or water into mechanical energy that drives generators.

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    Description

    Test your knowledge on key concepts from Science Chapter 8 with these flashcards. Learn about magnetite, magnetism, and the historical discovery of natural magnets. Perfect for students looking to reinforce their understanding of magnetic properties and fields.

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