Figure shows intensity versus wavelength graph of X-rays coming from coolidge-tube with molybdenum as target element :

The two peaks shown in graph correspond to `K_(alpha)` and `K_(beta)` X-rays
Voltage applied across Coolidge tube is (approximatly)

Options

A. 20 kV
B. 16 kV
C. 31 kV
D. 18 kV

Explanation

`1/(lambda_(Kb))=1/(lambda_(K alpha))+1/(lambda_(Lalpha))`
`1/(lambda_(Lalpha))=5.6 Å`

`eV=(hc)/(lambda)`
`V=(hc)/(elambda)=31xx10^(3)` volts