In the Coolidage tube experiment, if the applied voltage is increased to three times, the short wavelength limit of continuous X- ray spectrum shift by 20 pm. What is the intial voltage (in kV) applied to the tube?

Answer

`41`

Explanation

`:.` cut off wavelength for continuous x-ray is given as: `lamda_("min")=(hc)/(eV_(0))`
`:.(hc)/(eV_(0))=lamda` & `(hc)/(3eV_(0))=lamda-Deltalamda`
(`V_(0)=` accelerating voltage)
`impliesV_(0)=(2hc)/(3eDeltalamda)=41kV`