Modern Physics 4 Question 32
33. To produce characteristic $X$-rays using a tungsten target in an $X$-ray generator, the accelerating voltage should be greater than …… V and the energy of the characteristic radiation is …… eV. (The binding energy of the innermost electron in tungsten is $40 keV$ ).
(1983, 2M)
Analytical & Descriptive Questions
Show Answer
Solution:
- Minimum voltage required is corresponding to $n=1$ to $n=2$.
Binding energy of the innermost electron is given as $40 keV$ i.e. ionisation potential is $40 kV$. Therefore,
$$ V _{\min }=\frac{40 \times 10^{3} \frac{1}{1^{2}}-\frac{1}{2^{2}}}{\frac{1}{1^{2}}-\frac{1}{\infty}}=30 \times 10^{3} V $$
The energy of the characteristic radiation will be $30 \times 10^{3} eV$.
