Estimate the nuclear spins of the 3He and 4He nuclei.Explain your reasoning.
36. An air wedge is formed using two glass plates that are in contact along their left edge. When viewed by highly monochromatic light, there are exactly 4001 dark bands in the reﬂected light. The air is now evacuated (with the glass plates remaining rigidly ﬁxed) and the number of dark bands decreases to exactly 4000. The index of refraction of the air is: A. 0.00025 B. 0.00050 C. 1.00025 D. 1.00050 E. 1.00000, by deﬁnition ans: C 37. A glass (n =1 .6) lens is coated with a thin ﬁlm (n =1 .3) to reduce reﬂection of certain incident light. If λ is the wavelength of the light in the ﬁlm, the least ﬁlm thickness is: A. less than λ/4 B. λ/4 C. λ/2 D. λ E. more than λ ans: B 38. Two point sources, vibrating in phase, produce an interference pattern in a ripple tank. If the frequency is increased by 20%, the number of nodal lines: A. is increased by 20% B. is increased by 40% C. remains the same D. is decreased by 20% E. is decreased by 40% ans: A 39. If two light waves arecoherent: A. their amplitudes are the same B. their frequencies are the same C. their wavelengths are the same D. their phase diﬀerence is constant E. the diﬀerence in their frequencies is constant ans: D 40. To obtain an observable double-slit interference pattern: A. the light must be incident normally on the slits B. the light must be monochromatic C. the light must consist of plane waves D. the light must be coheren