Passage X Q 125131 MCAT 4

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Passage X Q 125-131 MCAT 4

• Q 125Which of the following changes to the
  circuit will decrease the electric field between
  the electrodes?
• . Increasing L by a factor of 2
• . Decreasing L by a factor of 2
• . Increasing R by a factor of 2
• . Decreasing R by a factor of 2

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Passage X Q 125-131 MCAT 4

• Q 126An electron is ejected from the cathode by
  a photon with an energy slightly greater than the
  work function of the cathode. How will the final
  KE of the electron upon reaching the anode
  compare to its initial PE immediately after it
  has been ejected?
• . It will be 2 times as large
• . It will be approximately equal
• . It will be 1/4 as large
• . It will be 0

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Passage X Q 125-131 MCAT 4

• Q 127When the number of photons incident on the
  cathode with energies above the value of the work
  function increases, which of the following
  quantities also increases?
• . The number of electrons ejected
• . PE of each ejected electron
• . Magnitude of the electric field between the
  electrodes
• . Speed of the electrons at the anode

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Passage X Q 125-131 MCAT 4

• Q 128Which of the following best describes the
  motion of an electron after it is ejected from
  the cathode?
• . It is stationary untill collisions propel it
  toward the anode
• . I moves with constant speed toward the anode
• . It accelerates toward the anode
• . It exits through a side of the vacuum photodiode

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Passage X Q 125-131 MCAT 4

• Q 129When the current in the circuit described
  in the passage is 1 X 10 -3 A, what power is
  dissipated as heat in the resistor?
• . 1 X 10-6 W
• . 1 X 10-4 W
• . 1 X 10-2 W
• . 1 X 10-1 W

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Passage X Q 125-131 MCAT 4

• Q 130Which of the following occurs when
  electrons are ejected from the cathode?
• . The voltage across the the electrodes reverses
  polarity
• . The voltage difference between the electrodes
  increases
• . Current flows through the circuit
• . The total resistance of the circuit increases

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Passage X Q 125-131 MCAT 4

• Q 131Increasing the frequency of each photon
  that is directed at the cathode will
• . decrease the number of photons ejected
• . increase the number of photons ejected
• . decrease the speed of the ejected electrons
• . increase the speed of the ejected electrons

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Passage X Q 125-131 MCAT 4

• Q Larrys QuestionIncreasing the frequency of
  each photon that is directed at the cathode will
• . decrease the number of electrons ejected
• . increase the number of electrons ejected
• . decrease the speed of the ejected electrons
• . increase the speed of the ejected electrons
• . Some combination of the above

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Passage VII Q 104-108 MCAT 3

• Q 104The conversion efficiency of Material B is
  0.42 at a frequency of
• . 3.5 X 10-15Hz
• . 2.8 X 102Hz
• . 2.8 X 1014Hz
• . 3.5 X 1015Hz

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Passage VII Q 104-108 MCAT 3

• Q 105The purpose of the reflection coating is
  most likely to
• . cool the device
• . Warm the device
• . maximize conversion efficiency
• . reduce the magnitude of the current

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Passage VII Q 104-108 MCAT 3

• Q 106Suppose that 2 identical photoelectric
  devices are connected to the same electrical
  circuit in parallel with each other. Compared to
  the voltage generated by a single device, the
  total voltage supplied to the circuit by the
  parallel devices will be
• . 4 times as large
• . 2 times as large
• . 1/2 as large
• . the same

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Passage VII Q 104-108 MCAT 3

• Q 108See graphs