Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Dual Nature of Radiation and Matter

Question:

For what kinetic energy of proton, will the associated de Broglie wavelength be 16.5 nm? (Given $m_p=1.675×10^{-27}kg,\,h=6.63×10^{-34}Js$)

Options:

$5.2×10^{-4}J$

$5.2×10^{-20}J$

$4.8×10^{-25}J$

$4.8×10^{-30}J$

Correct Answer:

$4.8×10^{-25}J$

Explanation:

Kinetic energy of proton, $K=\frac{1}{2}mv^2$

$=\frac{1}{2m}(mv^2)=\frac{1}{2m}(\frac{h^2}{λ^2})$  $(∵λ=\frac{h}{p})$

$=\frac{(6.63×10^{-34})^2}{2×1.675×10^{-27}×(16.5×10^{-9})^2}=4.8×10^{-25}J$