The photoelectric effect demonstrates that light

Answer: Has particle character — electrons are ejected only above a threshold frequency Below the work function, no photoelectrons emerge regardless of intensity — quantized photon energy must exceed the threshold.

If the frequency is doubled (above the threshold), the kinetic energy of ejected electrons:

Answer: Increases by hν (the additional photon energy) KEnew - KEold = h(2ν) - hν = hν, so KE rises by exactly hν of the original photon.

AP Chemistry · Topic 3.12

Photoelectric Effect Practice

Part of Properties of Substances and Mixtures.(SAP-8.B)

Practice questions

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Sample questions

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Sample 1difficulty 3/5
$The photoelectric effect demonstrates that light$
- A
  $Is unaffected by matter$
- B
  $Carries continuous energy$
- C
  $Is purely a wave$
- D
  $Has particle character — electrons are ejected only above a threshold frequency$
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Why
$Below the work function, no photoelectrons emerge regardless of intensity — quantized photon energy must exceed the threshold.$
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Sample 2difficulty 4/5
$A metal has work function (binding energy) Φ. Light of frequency ν shines on it. The kinetic energy of ejected electrons follows KE = hν - Φ.$
$If the frequency is doubled (above the threshold), the kinetic energy of ejected electrons:$
- A
  $Stays the same$
- B
  $Decreases$
- C
  $Increases by hν (the additional photon energy)$
  check_circle
- D
  $Doubles$
Why
$KE_new - KE_old = h(2ν) - hν = hν, so KE rises by exactly hν of the original photon.$
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