Question

The potential difference between the cathode and the target in a Coolidge tube is 120 kV. What can be the minimum wavelength (in $ \overset{0}{\mathop{A}}\, $ ) of the X-rays emitted by this tube?

• A. 0.4 $ \overset{0}{\mathop{A}}\, $
• B. 0.3 $ \overset{0}{\mathop{A}}\, $
• C. 0.2 $ \overset{0}{\mathop{A}}\, $
• D. 0.1 $ \overset{0}{\mathop{A}}\, $

Answer 1

Answer: (D)

Here: potential difference $ V=120\,kV=120\times {{10}^{3}}V $ From the formula for minimum wavelength $ {{\lambda }_{\min }}=\frac{hc}{eV}=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{(1.6\times {{10}^{-19}})\times 120\times {{10}^{3}}}=0.1\,\overset{\text{o}}{\mathop{\text{A}}}\, $