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Relativity, Quantum Physics, Quantum Mechanics and Atomic Physics 1. A group of astronauts travel from the earth to Beta Centauri 4.00 light-years (Ly) away at a speed of 0.750c. What is time of flight and the distance of Beta Centauri from the earth, as measured by the astronauts? 2. What speed must a particle attain before its kinetic energy is double the value predicted by the no relativistic expression, K. E. = = mv 3. An observer at rest relative to the earth measured the speed and the distance travelled by a muon formed in the earth's atmosphere to be 0.990c and 4.60 km. It then decayed into other particles. Calculate the elapsed time as measured by an observer at rest relative to the muon. 4. An isolated atom of a certain element emits light of wavelength 520 nm when the atom falls from its fifth excited state into its second excited state. The atom emits a photon of wavelength 410 nm when it drops from its sixth excited state into its second excited state. Find the wavelength of the light radiated when the atom makes a transition from its sixth to its fifth excited state? 5. (a) If an electron makes a transition from the n = 4 Bohr orbit to the n = 2 orbit, determine the wavelength of the photon created in the process. (b)Assuming that the atom was initially at rest, determine the recoil speed of the hydrogen atom when this photon is emitted?small ofdi sighs 6. The work-function for platinum is 6.35 eV.1 080 0 bre nouostenA 9t (a) Convert the value of the work-function from electron volts to joules. (b) Find the cutoff frequency for platinum? (c) What maximum wavelength of light is incident on platinum releases photoelectrons from the platinum's surface? (d) If light energy 8.50 ev is incident on zinc, what is the maximum kinetic energy of the ejected photoelectrons? Give the answer in ev. (e) For photons of energy 8.50 ev, what stopping potential would be required to arrest the current of photoelectric? 23