47. Induction is a process in which a moving produces a(n) c. magnetic field, electric field a. charge, current d. wave, electric field b. magnet, electric charge 47 48. The speed of an electromagnetic wave in any material is determined by the of that material. a. thickness c. electrical resistance b. density d. dielectric constant 48. For #49 and #50, write true or false. 49. In Thomson's cathode-ray tube, the cathode was negatively charged. 49 50. Ions in a mass spectrometer follow a circular path as they pass through a magnetic field. 50