Magnetic Fields and Currents Quiz
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Questions and Answers

What produces a current in dynamic microphones?

  • Pressure variations in sound waves (correct)
  • Coil of wire around the magnet
  • Fixed magnet at the center
  • Loudspeaker setup

    • In dynamic microphones, what causes the coil to move and induce current?

  • Current flow into the coil
  • Fixed magnet at the center
  • Pressure variations in sound waves (correct)
  • Magnetic field from the coil

    • Which principle is involved in the operation of dynamic microphones?

  • Newton's Third Law
  • Ohm's Law
  • Boyle's Law
  • Fleming's Left Hand Rule (correct)

    • What interacts to cause the movement of the cone in loudspeakers?

    <p>Magnetic field from the magnet and current</p> Signup and view all the answers

    What is responsible for producing pressure variations in loudspeakers?

    <p>Movement of the cone</p> Signup and view all the answers

    What happens if the magnetic field changes while a current flows in a conductor?

    <p>The current will produce its own magnetic field that opposes the change inducing it</p> Signup and view all the answers

    How is direct current (DC) produced in an electric generator like a dynamo?

    <p>By connecting the ends of the coil of wire to a split ring commutator</p> Signup and view all the answers

    In an alternator, what type of current is produced when the coil of wire rotates between two permanent magnets?

    <p>Alternating current (AC)</p> Signup and view all the answers

    What results from more coils on the secondary coil of a transformer?

    <p>Step up transformer with increased voltage</p> Signup and view all the answers

    What happens if the primary current in a transformer is direct current (DC)?

    <p>It produces a constant magnetic field and fails to induce a current in the secondary coil</p> Signup and view all the answers

    What principle states that when a wire cuts through a magnetic field, it induces an electromotive force (emf) or voltage?

    <p>Faraday's Law of Electromagnetic Induction</p> Signup and view all the answers

    What dictates the direction of the magnetic field produced by a current-carrying wire?

    <p>The Right Hand Grip Rule</p> Signup and view all the answers

    In a solenoid, why does having an iron core in the center increase the strength of the magnetic field?

    <p>It makes it easier for magnetic field lines to pass through than air</p> Signup and view all the answers

    What rule is used to determine the direction of force felt when a wire carrying current interacts with a magnetic field?

    <p>Fleming's Left Hand Rule</p> Signup and view all the answers

    What is the relationship between magnetic flux density and the force acting on a current-carrying wire in a magnetic field?

    <p>Direct relationship</p> Signup and view all the answers

    How does an electric motor generate motion?

    <p>By using permanent magnets and a coil of current-carrying wire</p> Signup and view all the answers

    What phenomenon results in a potential difference being induced across a conductor?

    <p>Electromagnetic Induction</p> Signup and view all the answers

    When there is relative movement between a conductor and a magnetic field, what is induced across the conductor?

    <p>Potential difference</p> Signup and view all the answers

    What happens to the force exerted on a wire when its direction is perpendicular to the magnetic field lines?

    <p>It decreases</p> Signup and view all the answers

    What determines the strength of a magnetic field around a wire?

    <p>The cross-sectional area of the wire</p> Signup and view all the answers

    What shape does the magnetic field in a solenoid resemble?

    <p>Helix or spiral</p> Signup and view all the answers

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