Magnetism and Hysteresis Loop
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Questions and Answers

What is the term for the magnetic retentivity that remains in a substance even when the magnetic field is zero?

  • Saturation point
  • Hysteresis loss
  • Residual magnetism (correct)
  • Coercive force

    • What is the point at which the material is totally demagnetized?

  • Point D
  • Point C (correct)
  • Point B
  • Point A

    • What is the energy loss caused by the friction of molecules in the core of electric machines?

  • Hysteresis loss (correct)
  • Magnetic retentivity
  • Coercive force
  • Hysteresis

    • What is the direction of the magnetic field produced by an alternating current?

    <p>Continually changing direction</p> Signup and view all the answers

    What is the purpose of the coercive force in a magnetic material?

    <p>To remove the material's retentivity</p> Signup and view all the answers

    What is the term for the cycle of magnetization and demagnetization in a ferromagnetic material?

    <p>Hysteresis loop</p> Signup and view all the answers

    What is the typical amount of energy stored in a piezoelectric generator after a tap or press?

    <p>0.00001 joules</p> Signup and view all the answers

    What is the main goal of improving the piezoelectric material itself?

    <p>To make the material more efficient at converting mechanical energy into electrical energy</p> Signup and view all the answers

    Why is placing the piezoelectric material in certain locations a focus of research?

    <p>To increase the frequency of deformation</p> Signup and view all the answers

    What is the piezoelectric effect?

    <p>The conversion of mechanical energy into electrical energy</p> Signup and view all the answers

    What is an example of a common piezoelectric material?

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

    How much energy does a typical cell phone battery store?

    <p>18,000 joules</p> Signup and view all the answers

    What is the work function represented as for metals?

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

    What is the energy difference between the conduction band minimum and the vacuum energy level?

    <p>Electron affinity</p> Signup and view all the answers

    What type of contact is formed when a metal and a semiconductor material are brought together with no electron movement?

    <p>Ideal MS contact</p> Signup and view all the answers

    What is the purpose of the Schottky diode when used as a rectifier contact?

    <p>To allow current flow in one direction</p> Signup and view all the answers

    What is the condition for the formation of a Schottky contact when φm > φs?

    <p>The work function of the metal is greater than the work function of the semiconductor</p> Signup and view all the answers

    What type of semiconductors can form the Schottky contact?

    <p>Both n-type and p-type semiconductors</p> Signup and view all the answers

    What is the Schottky barrier?

    <p>The potential energy barrier formed at the metal-semiconductor junction</p> Signup and view all the answers

    What is the consequence of electrons transferring from the semiconductor to the metal in a Schottky barrier contact?

    <p>A negative charge in the metal and a positive charge in the semiconductor</p> Signup and view all the answers

    What is the energy difference between the band edge with majority carriers and the Fermi energy of the metal?

    <p>Barrier height ΦB</p> Signup and view all the answers

    Under what condition is the equilibrium band structure for a metal and a n-type semiconductor established?

    <p>When the applied bias VA is 0V</p> Signup and view all the answers

    What is the reason for the formation of a depletion region at the semiconductor surface?

    <p>The transfer of electrons from the semiconductor to the metal</p> Signup and view all the answers

    What is the relationship between the work function of semiconductors and the electron affinity?

    <p>The work function of semiconductors is related to the electron affinity and the conduction band</p> Signup and view all the answers

    What happens to the depletion region as the applied voltage is continuously increased?

    <p>It becomes thinner and finally disappears</p> Signup and view all the answers

    Why does a positive current get generated across the MS junction?

    <p>More electrons diffuse from the semiconductor towards the metal</p> Signup and view all the answers

    What is the effect of increasing the applied voltage on the electrons in the MS junction?

    <p>Electrons find it easier to overcome the surface barrier</p> Signup and view all the answers

    What happens to the current as the VA is kept increasing?

    <p>It increases rapidly</p> Signup and view all the answers

    What is the direction of the current in the MS junction when VA is positive?

    <p>From the semiconductor to the metal</p> Signup and view all the answers

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