If the integrated intensity of the white spectrum for x-ray tube is given by,

If the integrated intensity of the "white" spectrum for x-ray tube is given by, Iw=AiZVVn,n2 ( i is the applied current; Z is the atomic number of the target; V is the applied voltage; A is a proportionality constant), and the intensity of the Ka lines is given by, Ik=Bi(VVk)1.5 What is the relation between applied voltage (V) and the excitation potential of the target material (Vk) to get maximized Ik/Iw ? Input your numerical (integer) answer in terms of (V/Vk) in the blank below, e.g., if your answer is V= 8Vk for maximum Ik/Iw, input "8" in the blank. [hint: take the first and second V derivative of (Ik/Iw).]