A beam of electrons striking a copper target produces X-rays. Its spectrum is as shown. Keeping the voltage same if the copper target is replaced with a different metal, the cut-off wavelength and characteristic lines of the new spectrum will change in comparison with old as:

Options

A. Cut-off wavelength will remain unchanged while characteristic lines will be different.
B. both cut-off wavelength and characteristic lines will remains unchanged
C. both cut-off wavelength and characteristic lines will be different.
D. cut-off wavelength wll be different while characteristic lines will remain unchanged.

Answer

A

Explanation

Cut-off wavelength of emitted X-rays depends on maximum kinetic energy of encident electrons on the target and is independent of nature of target. The characteristic lines depend on nature of material of target.