Electron is accelerated by 100 volt potential difference. Its wavelength will be comparable to that of :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → X-rays
An electron accelerated through a potential difference \( V \) gains kinetic energy \( eV \), and its de Broglie wavelength is
\( \displaystyle \lambda = \frac{h}{\sqrt{2 m e V}} = \frac{1.227}{\sqrt{V}}\,\mathrm{nm} \)
\( \displaystyle \lambda = \frac{1.227}{\sqrt{100}}\,\mathrm{nm} = 0.1227\,\mathrm{nm} \approx 1.2\,\mathring{\mathrm{A}} \)
X-rays have wavelengths from about \( 10\,\mathrm{nm} \) down to \( 10^{-4}\,\mathrm{nm} \), so this wavelength lies in the X-ray range.