Question

Find the maximum frequency of the x - rays emitted by an x - ray tube operating at 20 kV.

1. 2.41 × 10¹⁸ Hz
2. 9 × 10¹⁸ Hz
3. 4.8 × 10¹⁸ Hz
4. 4.14 × 10¹⁸ Hz

Answer 1

Correct Answer - Option 3 : 4.8 × 10¹⁸ Hz

For maximum frequency, the total kinetic energy should be converted to the X - ray photon.

\(\begin{array}{l} \Rightarrow h\nu \; = \;eV\\ \nu \; = \;\frac{{eV}}{h}\; = \;\frac{{e \times 20 \times {{10}^3}}}{{4.14 \times {{10}^{ - 15}}eV - s}} \end{array}\) 

= 4.83 × 10¹⁸ Hz