$20 \ kV$ electrons can produce $X$-rays with a minimum wavelength of

What $kV$ potential is to be applied on an $X$-ray tube so that the minimum wavelength of emitted $X$-rays may be $1 \text{ Å}$? $(h = 6.625 \times 10^{-34} \text{ J-s})$

The minimum wavelength of the $X$-rays produced at an accelerating potential $V$ is $\lambda$. If the accelerating potential is changed to $2V$, then the minimum wavelength would become:

If the frequency of $K_\alpha$ $X$-rays emitted from the element with atomic number $31$ is $v$,then the frequency of $K_\alpha$ $X$-rays emitted from the element with atomic number $51$ would be:

Bragg's law for $X$-rays is

The wavelength of the ${K_\alpha}$ line for an element of atomic number $29$ is $\lambda$. Then the wavelength of the ${K_\alpha}$ line for an element of atomic number $15$ is (Take Moseley's constant $b = 1$ for both elements).