In alpha particle scattering experiment, when gold foil is in 1mm thickness, The number of particles detected at the opposite side of the source becomes zero but not just decreases. (92Q7)
Usually a radioactive source with X to 1X hours half life emitting gamma radiation is used for injection in patient. The reasons include:
1.The half-life is long enough for doctor to diagnose the patient.
2.The half-life is short so that the radiation will not retain inside the body for a long time causing little harm to the body
3.Gamma ray get high penetrating power so that it can be detected outside the body.
(93Q7)
沒有留言:
張貼留言