Lithium was one of the metals studied by the American physicist Robert Millikan in his research on the photoelectric effect. When illuminate

Question

Lithium was one of the metals studied by the American physicist Robert Millikan in his research on the photoelectric effect. When illuminated with blue light of frequency 6.64 x 10″ Hz, the photoelectrons ejected from a lithium surface have a maximum kinetic energy of 0.332 eV. What is the threshold frequency for lithium? For this problem, let the value of Planck’s constant, h, be 6.63 x 10J’s

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Kiệt Gia 5 years 2021-08-19T12:21:43+00:00 1 Answers 15 views 0

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  1. huyenthanh
    0
    2021-08-19T12:23:38+00:00
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    Answer:

     f = 7.9487 10¹³ Hz

    Explanation:

    The photoelectric effect was correctly explained by Einstein assuming that the radiation is composed of photons, which behave like particles.

               hf = K + Ф

    It indicates the frequency and the kinetic energy, let’s look for the work function

              Ф = hf – K

    let’s reduce the magnitudes to the SI system

              K = 0.332 eV (1.6 10⁻¹⁹ J / 1 eV) = 0.5312 10⁻⁻¹⁹ J

    let’s calculate

              Ф = 6.63 10⁻⁻³⁴  6.64 10¹¹ – 0.5312 10⁻¹⁹

              Ф = 4.40 10⁻²² – 0.5312 10⁻¹⁹

              Ф = 5.27 10⁻²⁰ J

    for the minimum frequency that produces photoelectrons, the kinetic energy is zero

               hf = Ф  

               f = Ф / h

               f = 5.27 10⁻²⁰ / 6.63 10⁻³⁴

               f = 7.9487 10¹³ Hz

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