Question

Cutoff wavelength of X-rays coming from a Coolidge tube depends on the (a) target material

Answer 1

Cutoff wavelength (λmin) is given by

λmin = hceV

Here,

h = Planck's constant
c = Speed of light
V = Accelerating voltage
e = Charge of electron

Clearly, a cutoff wavelength depends on accelerating voltage. It does not depend on the target material, separation between the target and the temperature of the filament.

Answer: Accelerating voltage