If the kinetic energy of an electron is 100 eV , what is the wavelength
PHYSICS
WAEC 2022
If the kinetic energy of an electron is 100eV, 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
Correct Answer: D. 5.50 x 10\(^{-14}\)m
Explanation
de broglie wavelength formula in terms of kinetic energy:
λ = \(\frac{h}{\sqrt{2mE}}\)
λ = \(\frac{6.6 *10^{-34}}{\sqrt{2 *9.1*10^{-31} *100 }}\)
λ = 5.50 x 10\(^{-14}\)m
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