$X$-rays of wavelength $0.140 \,nm$ are scattered from a block of carbon. What will be the wavelengths of $X$-rays scattered at $90^{\circ}$ (in $\,nm$)?

The energy of the $K_\alpha$ $X$-ray line of an element is $8578$ units,and the energy of the $L$ level is $-2859$ units. The energy of the $K$ level is . . . . . . units.

In an $X$-ray tube,when the accelerating voltage is increased from $10 \ kV$ to $20 \ kV$,the difference between the wavelength of the $K_\alpha$ line and the short-wavelength limit of the continuous spectrum increases by a factor of $3$. The atomic number of the target element is:

The figure represents the observed intensity of $X-$rays emitted by an $X-$ray tube as a function of wavelength. The sharp peaks $A$ and $B$ denote:

The minimum wavelength of $X$-rays produced in a Coolidge tube operating at $40 \ kV$ is ..... $\mathring A$.

$X$-rays are produced by accelerating electrons through a potential difference $V$ and letting them strike a metal target of atomic number $Z$. The highest frequency of the $X$-rays produced is proportional to: