Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Dual Nature of Radiation and Matter

Question:

What is the de Broglie wavelength of an electron with kinetic energy of 81 eV?

Options:

0.136 nm

0.712 nm

0.512 nm

4 nm

Correct Answer:

0.136 nm

Explanation:

The de Broglie wavelength is given by

\(\lambda \) =\(\frac{h}{\sqrt {2mK}}\)

Kinetic energy, K = 81 eV = 81×1.6×10-19 J

\(\lambda \) = \(\frac{6.626 × 10^{-34}}{\sqrt{2 × 9.1 × 10^{-31} × 81 × 1.6 × 10^{-19}}}\)

                   = 0.136 nm