$X$-rays were discovered by

If the operating potential of an $X-$ray tube is $50 \text{ kV}$,the velocity of $X-$rays coming out of it is

The maximum distance between the inter-atomic planes of a crystal is $10^{-7} \ cm$. The maximum wavelength of $X$-rays that can be studied by this crystal is ........... $\mathring{A}$.

If a voltage applied to an $X$-ray tube is increased to $1.5$ times, the minimum wavelength $(\lambda_{\min})$ of an $X$-ray continuous spectrum shifts by $\Delta \lambda = 26 \, pm$. The initial voltage applied to the tube is:

When an $X$-ray tube operates at $60 \ kV$,the observed tube current is $50 \ mA$. Assuming that the total energy of the electrons is converted into heat,the rate of heat production at the anode in $cal/s$ is:

In an $X$-ray tube,the wavelength of characteristic $X$-rays is a property of .......