40. What should he the height ofa dipole antenna (of dimensions 1.\" wavelength) if it is to transmit 1200 kHz W a. l 1.4 m b. 60 cm c. 1.12 m d. 62.5 m e. 250 m EDP-99'.\" 41. At every instant the ratio of the magnitude of the electric to the magnetic "I" eld in an electromagnetic Wave in vacuum is equal to the speed of radio waves the speed of light the speed of gamma rays. 1119f the above. only (a) and (b) above. 42. What is the radius ofthe rst electron orbit? a. 1.1 A b. 0 65 A c. 0.55 A d. 2.0A e. None ofthe above 43. What is the wavelength of a transition between 11:3 and n:l orbits? at. 5500A b. 100A c.10,27'0A r1. 12,800A e 1027 A 44. What is an isotope? a. Atoms with the same number of neutrons, but different numbers ofprolons b. Atoms with the same number of protons, but differmt numba' of electrons e. Atoms with the some atomic mass, but different atomic number Z d. Atoms with the same atomic number Z, but different atomic mass e. None ofthe above 45. What are the three forms of radiation that comes from a radioactive nucleus? 71. alpha, beta: and electrons b alpha= positrons, and electrons a. beta, positrons and gamma :1 alpha= beta and gamma e. neutrons: protons and gamma 46. What is an alpha particle? a. A highly energized electron b A Helium nucleus 1:. RachEmt energyr d A highly radioactive isotope e. None ofthe above