(xi) A certain particle at rest has a lifetime of 2.52 μs. What must be the speed of the particle for its lifetime observed to be 8.32 μs? (a) 0.985c (b) 0.953c (c) 0.913c (d) 0.302c (e) None of the above (xii) A source at rest emits light of wavelength 500 nm. When it is moving at 0.90c toward an observer, the observer detects light of wavelength: (a) 26 nm (b) 115 nm (c) 500 nm (d) 2200 nm (e) 9500 nm