An X-ray tube emits X-rays with a wavelength of 1.0 x 10-11 m. Calculate the potential that must be applied across the X-ray tube to give each incident electron its energy, in volts.

A ) 0.6 x 105
B ) 1.2 x 105
C ) 2.4 x 105
D ) cannot be determined

The potential that must be applied across the X-ray tube to give each incident electron the appropriate energy to goose X-rays with a wavelength of 1.0 x 10-11 m out of the anode cannot be determined from the given information. (D)

The energy (or wavelength) of the emitted X-rays is NOT directly determined by the energy of the incident electrons in the x-ray tube. It's determined mainly by the substance of which the anode is composed, and the electron configuration of the substance.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.