X-rays of wavelength \( \lambda = 1\,\mathring{\mathrm{A}} \) have frequency
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 3 \times 10^{18}\,\mathrm{Hz} \)
X-rays are electromagnetic waves, so they travel at the speed of light and \( c = \nu\lambda \).
\( \lambda = 1\,\mathring{\mathrm{A}} = 10^{-10}\,\mathrm{m} \)
\( c = 3\times10^{8}\,\mathrm{m\,s^{-1}} \)
\( \displaystyle \nu = \frac{c}{\lambda} = \frac{3\times10^{8}\,\mathrm{m\,s^{-1}}}{10^{-10}\,\mathrm{m}} = 3\times10^{18}\,\mathrm{Hz} \)
Note: A similar question was also asked in CUET (UG) 2023 on 11-06-2023 (Slot 3).