An X-ray tube is operated at `50 kV and 20 m A`. The target material of the tube has mass of `1 kg` and specific heat `495 J kg ^(-1) `^(@)C^(-1)`. One perent of applied electric power is converted into X-rays and the remaining energy goes into heating the target. Then,

Options

A. the average rate of rise of temperature of the target would be `2_(0)C//sec`
B. the minimum wavelength of the `X`-rays emitted is about `0.25xx10^(-10)m`
C. a suitable target material must have a high melting temperature
D. a suitable target material must have thermal conductivity

Answer

B

Explanation

Power reaching the target `p=Vi=1000W` .
The rate of heat production =`(99)/(100)xx1000=990W`
`P=(dttheta)/(dt)=(mstheta)/(dt)=990Rightarrow(dttheta)/(dt)=2^(0)c//_(s)` and `lambda_(min)=(hc)/(eV)`