Final answer:
The statement is true as approximately 1% of the energy in an x-ray tube is converted into light (x-ray photons), with the rest lost as heat. This speaks to the efficiency of x-ray photon production in this process.
Step-by-step explanation:
The statement that when electrons strike the target, about 1% of the energy produced is light is true. This refers to the process in x-ray tubes where high energy electrons hit a metal target and the energy conversion results in a very small fraction being emitted as x-ray photons (which is a form of light), with the majority of the energy being dissipated as heat. The photoelectric effect is intimately related to this phenomenon where the ejected electrons come as a result of the interaction between the light (photons) and the material. The number of ejected electrons is proportional to the intensity of the light, as long as the light has an energy above a certain threshold level.