1. Triplets A and B board spaceships and head away from Earth in opposite directions, each traveling the same distance at the same speed before returning to Earth. Triplet C remains on Earth. Which expression describes the triplet's relative ages once they're reunited on Earth?




... Answer is C. A = B ＜ C
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2. If a spaceship travels from Earth to a planet in the Alpha Centauri star system, which observer measures the proper time for the trip?




... Answer is C. an observer on the spaceship
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3. When you compress a spring between your fingers, its mass




... Answer is A. Increase
A compressed spring has more mass than an uncompressed spring


4. By doubling the absolute temperature of the black body, the total energy radiated will change by a factor of




... Answer is D. 16
According to Stefan-Boltzmann Law, E = σ T⁴


5.  According to Einstein, increasing the brightness of a beam of light without changing its color will increase:




... Answer is A. the number of photons.
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6. Sources of red, blue, and yellow light each emit light with a power of 50 mW. The source which emit more photons is




... Answer is A. red
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7. Of the following energies for photons, which is the least energy that could result in photoelectron production if the work function is 3.00 eV? :




... Answer is C. 3.50 eV
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8. In a Compton scattering experiment at which angle does the electron carries maximum energy? (Assume that initially, the target electron is at rest).




... Answer is B. 90°
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9. If X-rays are scattered from protons instead of electrons, the change in their wavelength for a given angle of scattering




... Answer is B. decreases
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10. Pair production cannot take place in a vacuum because.




... Answer is B. Momentum is not conserved
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11. According to the de-Broglie equation which one has the smallest wavelength associated with it




... Answer is C. α-particle
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12. An electron and a proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is




... Answer is D. greater than the kinetic energy of the proton
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13. In an Electron microscope, the light source is replaced by a beam of very fast moving




... Answer is A. electron
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14.  According to Heisenberg, as the uncertainty in the measurement of a particle's momentum is reduced by a factor of 2, by what factor is the uncertainty in that same particle's position changed?




... Answer is c. 2
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