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:

What is the difference between soft and hard $X-$rays?

Find the wavelength of $K_\alpha$ $X$-rays.

An electron beam is accelerated by a potential difference of $V$ and strikes a metal target to produce $X$-rays. For which of the following values of $V$ (in $kV$) will the $X$-ray wavelength be the shortest?

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

An $X$-ray tube operates at $50 \, kV$ and $20 \, mA$. The target material has a mass of $1.0 \, kg$ and a specific heat capacity of $495 \, J \cdot kg^{-1} \cdot ^\circ C^{-1}$. One percent of the applied electrical power is converted into $X$-rays,and the remaining energy is used to heat the target. Then:
$(1)$ $A$ suitable target material should have a high melting point.
$(2)$ $A$ suitable target material should have low thermal conductivity.
$(3)$ The rate of rise of temperature of the target is $2 \, ^\circ C/s$.
$(4)$ The minimum wavelength of the emitted $X$-rays is $0.25 \, \mathring{A}$.