Final answer:
The provided information relates to different aspects of physics, such as induced electric currents, Ohm's Law, and the effects of magnetic fields on magnetic strips. A definitive answer to the control over mA selection in falling load generators is not given in the excerpts.
Step-by-step explanation:
The original question regarding control over the mA selection when using a falling load generator appears to be related to medical radiographic imaging or similar technology. However, the provided information pertains to different concepts in physics, so a direct answer to the question is not possible from the given excerpts. Nevertheless, it is important to address the provided physics information:
When a bar magnet is dropped through a copper tube, an electric current is indeed induced in the tube due to the changing magnetic field, which is consistent with electromagnetic induction principles (Faraday's Law). So the answer to the referenced statement would be true.
Regarding Ohm's Law, it states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance. This is an essential principle in the study of electricity.
Finally, for magnetic fields, it is recommended to keep credit cards with magnetic strips away from permanent magnets because the strong magnetic field can demagnetize the strip, rendering the card unusable. Hence, the answer is true.