The Speed of Light and Electromagnetic Waves, Exams of Quantum Physics

Download The Speed of Light and Electromagnetic Waves and more Exams Quantum Physics in PDF only on Docsity! PHYS 1400 Sample Exams: Light and Color 1. The idea that the speed of light is a constant that could be measured A) dates back to Democritus, who hypothesized that atoms move at the speed of light. B) goes back as far as Galileo, but he was not able to make the measurement accurately. C) is laughable, because we know now that light travels instantaneously through any medium. D) was disproved conclusively with Maxwell's equations. 2. How fast do electromagnetic (em) waves travel? A) 70 mph, the same speed as a cheetah. B) The same speed as light. C) Faster than sound waves, but slower than light. D) They do not travel; the wave stays put. 3. What was the significance of Hertz's experiment in 1887? It showed that A) a beam of light knocks electrons off a metal foil, proving that light and electricity were related. B) alpha particles are deflected by atomic nuclei, proving that the nucleus is positively charged. C) radio waves are electromagnetic, opening the door for Marconi and wireless communication. D) an oscillating circuit creates gravitational waves, demonstrating that gravity is magnetic in nature. 4. Electromagnetic waves A) include both radio waves and sound waves. B) are longitudinal and require a medium to travel through. C) are transverse and require a medium to travel through. D) include gamma rays, ultraviolet light, and infrared radiation. 5. The electromagnetic spectrum includes A) radio, television, and sound waves. C) visible light, but no other types of waves. B) radio, sound, and seismic waves. D) radio, infrared, ultraviolet, and gamma rays. 6. The electromagnetic spectrum A) is discrete: you can only have wavelengths or frequencies that are whole numbers. B) is continuous: there are no "forbidden" values for wavelength or frequency. C) is garbled: there are certain frequencies that correspond to more than one wavelength. 7. Radio waves have a much lower frequency than x-rays. This means that radio waves A) have less energy than x-rays. C) have the same energy as x-rays. B) have more energy than x-rays. D) have shorter wavelength than x-rays. 8. Ultraviolet (UV) waves have a much higher frequency than infrared (IR). This means that UV waves A) have less energy than IR. C) have the same energy as IR. B) have more energy than IR. D) have longer wavelength than IR. 9. Compare infrared waves with x-rays. A) They are unrelated phenomena, so there is nothing to compare. B) Infrared waves are lower frequency, lower energy electromagnetic waves. X-rays are high frequency and high energy electromagnetic waves. C) Backwards! Both are electromagnetic waves, but infrared waves have higher frequency and energy. D) Infrared waves are the electro waves, and x-rays are the magnetic waves. 10. The wavelength of an electromagnetic wave A) is a measure of its speed. C) decreases with increasing frequency. B) increases with increasing frequency. D) is unrelated to its frequency. 11. The frequency of a light wave A) is a measure of its speed. C) decreases with increasing wavelength. B) increases with increasing wavelength. D) is unrelated to its wavelength. 12. The energy of a light wave A) is a measure of its speed. C) decreases with increasing frequency. B) increases with increasing frequency. D) is unrelated to its frequency. 13. The speed of light A) is fastest in a vacuum. C) increases as the frequency increases. B) is 300,000 m/s. D) increases as the wavelength increases. 14. Why don't you also need to apply "radio screen" when you apply your ultraviolet-blocking sunscreen lotion before you spend the day outdoors? A) Because if the lotion blocks UV rays, it will automatically block all other forms of em radiation. B) Because radio waves have less energy, so they will not damage your skin the way UV rays do. C) Because humans have evolved to be immune from damage from everything except UV rays. D) Because none of the radio radiation from the sun gets down to the surface of the earth. 15. The sun emits em radiation A) only in the range of visible frequencies; no energy is emitted as radio or ultraviolet. B) across the entire em spectrum. It emits as much energy in the visible range as in the gamma range. C) across the entire spectrum, but most of the energy is emitted in the visible range of frequencies. D) only at very low frequencies. No energy is emitted at frequencies above the visible. 16. How are photons created? A) The Photon Fairy sprinkles Sparkle Dust while we sleep, and it starts to glow when the sun comes up. B) A vibrating electron will emit a packet of pure energy. This quantum of energy is a photon. C) A small piece of an electron breaks off, and carries photonic energy in the form of electric charge. D) The neutrons in the nucleus emit photons, which keep the protons from ejecting each other. 17. Light incident on a surface may be A) transmitted, if the medium is transparent. C) absorbed, causing the medium to heat up. B) reflected, causing the medium to heat up. D) either A or C. 18. When an electron absorbs the energy of a photon, A) any electron might absorb any amount of energy from any incoming photon. It's totally random. B) it spirals in to the nucleus of the atom. When the electron crashes into the nucleus, the energy released is what we have labeled electromagnetic radiation. C) the electron can only absorb a photon with exactly the amount of energy required to jump up to a higher energy orbit. The quantum of energy depends on the type of atom. D) it jumps up to a higher energy orbit. Then it immediately spits out a photon with half as much energy, taking it back down half way. At some random later time, it will spit out a second photon with the rest of the energy and drop all the way back down to its original orbit. 19. Light transmission occurs as A) a photon "zigs" and "zags" its way through a medium, avoiding the electrons and the nuclei. B) electrons absorb and reemit the same photon, like passing a hot potato. C) photons are absorbed and reemitted, but it's not the same photon over and over. D) striking photons cause electrons on the surface to vibrate and shoot photons back out the way the came. 20. Steel is opaque to visible light because A) visible photons are allowed through the medium, and emerge out the other side. B) visible photons are absorbed by the medium. Many are reemitted (reflected), and others are absorbed, but none have enough energy to actually penetrate the steel and emerge out the other side. C) it has no electrons, so it cannot absorb photons of any frequency. Steel is impenetrable to all forms of electromagnetic radiation. 21. The windshield of your car is A) opaque to all forms of electromagnetic radiation. B) transparent to all forms of electromagnetic waves. C) transparent to UV and IR, but opaque to visible light. D) reflective to UV, absorptive to visible, and permeable to IR frequencies. E) transparent to visible, but opaque to UV and IR frequencies of radiation.