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If the kinetic energy of an electron is 100 eV, what is the wavelength of...

Physics
WAEC 2022

If the kinetic energy of an electron is 100 eV, what is the wavelength of the de-Broglie wave associated with it? [h = 6.6 x 10\(^{-34}\) J s, e = 1.6 x 10\(^{-19}\)C, m\(_{e}\), = 9.1 x 10\(^{-31}\) kg]

  • A. 1.22 x 10\(^{-10}\)m
  • B. 4.10 x 10\(^{-10}\)m
  • C. 3.90 x 10\(^{-10}\)m
  • D. 5.50 x 10\(^{-14}\)m
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Correct Answer: Option A
Explanation

de broglie wavelength formula in terms of kinetic energy:

 λ = \(\frac{h}{\sqrt{2mE}}\) 

 λ = \(\frac{6.6 \times 10^{-34}}{\sqrt{2 \times 9.1 \times10^{-31} \times100\times 1.6 \times 10^{-19}}}\)

 λ = 1.22 x 10\(^{-10}\)m

NOTE; E = 100eV = 100 x 1.6 x 10\(^{-19}\)J


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