9. The frequency of the hydrogen H1 line is 1.42 GHz which is observed frequently in radio astronomy. A H1 line emitted by a distant astronomical object is observed at 0.765 GHz due to Doppler redshift. Given the Hubble constant H = 17×10-3 m/s/ly, where ly stands for light year's law v = HR, where v is the recessional velocity of the astronomical object, to estimate the distance R between Earth and the recessional astronomical object. (A) 9.7×109 ly (B) 1.7×106 ly (C) 3.7×103 ly (D) 7 ly

10. Figure 5 illustrates a particle accelerator called cyclotron. It is composed of two hollow metal semicircular containers D1 and D2, and a source of charged particle, e.g., proton, at the center. A high frequency alternating electric potential is applied to D1 and D2, which will generate an alternating electric field in the gap between D1 and D2. A uniform and static magnetic field B is applied vertically to bend the trajectory of a charged particles in a cyclotron. In order to accelerate the charged particle, at each time when the particle passes the gap, one has to change the direction of . Please calculate the angular frequency of the alternating electric voltage in terms of particle mass m, charge e, magnitude of the static magnetic field . (A)(B)(C)(D)

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