The wavelength of a microscopic particle of mass \(9.1 \times 10^{-31} \mathrm{~kg}\) is \(182…

The wavelength of a microscopic particle of mass \(9.1 \times 10^{-31} \mathrm{~kg}\) is \(182 \mathrm{~nm}\), its kinetic energy in \(\mathrm{J}\) is \(\left(h=6.625 \times 10^{-34} \mathrm{~J} \mathrm{~s}\right)\)
  1. \(728 \times 10^{-23}\)
  2. \(7.28 \times 10^{-24}\)
  3. \(3.64 \times 10^{23}\)
  4. \(3.64 \times 10^{24}\)

Solution

Given, mass of particles \(=9.1 \times 10^{-31} \mathrm{~kg}\) Wavelength \((\lambda)=182 \mathrm{~nm}=182 \times 10^{-9} \mathrm{~m}\) According to de-Broglie equation, \(\begin{aligned} \lambda & =\frac{h}{m v} \Rightarrow v=\frac{h}{m \times \lambda} \\ v & =\frac{6.625 \times 10^{-34} \mathrm{Js}}{91 \times 10^{-31} \mathrm{~kg} \times 182 \times 10^{-9} \mathrm{~m}} \\ & =0.004 \times 10^6 \mathrm{~m} / \mathrm{s}=4 \times 10^3 \mathrm{~m} / \mathrm{s} \end{aligned}\) Therefore, kinetic energy, \(\begin{aligned} \mathrm{KE}=\frac{1}{2} m v^2 & =\frac{1}{2} \times 9 \mathrm{I} \times 10^{-31} \times\left(4 \times 10^3\right)^2 \\ & =7.28 \times 10^{-24} \mathrm{~J} \end{aligned}\)

Asked in: AP EAMCET 2019 (20 Apr Shift 1)

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