Question

An X-ray tube is operated at 66 kV. Then, in the continuous spectrum of the emitted X-rays

• A. wavelengths 0.01 nm and 0.02 nm will both be present
• B. wavelengths 0.01 nm and 0.02 nm will both be absent
• C. wavelength 0.02 nm will be absent but wavelength 0.01 nm will be present
• D. wavelength 0.01 nm will be absent but wavelength 0.02 nm will be present

Answer 1

The correct option is D wavelength 0.01 nm will be absent but wavelength 0.02 nm will be present

Here, $V=66kV=66000V$
Now, ${\lambda }_{min}=\frac{hc}{eV}=\frac{6.6\times {10}^{-34}\times 3\times {10}^8}{1.6\times {10}^{-19}\times 66,000}=1.87\times {10}^{-11}m=0.0187nm$
Since wavelength 0.01 nm is less than ${\lambda }_{min}$, it will be absent from the continuous spectrum.
Hence, the correct choice is (d).