Light - Properties of Matter - Solved Exam, Exams of Quantum Physics

Download Light - Properties of Matter - Solved Exam 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 B) goes back as far as Galileo, but he was not able to make the measurement accurately. 2. How fast do electromagnetic (em) waves travel? B) The same speed as light. 3. What was the significance of Hertz's experiment in 1887? It showed that C) radio waves are electromagnetic, opening the door for Marconi and wireless communication. 4. Electromagnetic waves D) include gamma rays, ultraviolet light, and infrared radiation. 5. The electromagnetic spectrum includes D) radio, infrared, ultraviolet, and gamma rays. 6. The electromagnetic spectrum B) is continuous: there are no "forbidden" values for wavelength or frequency. 7. Radio waves have a much lower frequency than x-rays. This means that radio waves A) have less energy than x-rays. 8. Ultraviolet (UV) waves have a much higher frequency than infrared (IR). This means that UV waves B) have more energy than IR. 9. Compare infrared waves with x-rays. B) Infrared waves are lower frequency, lower energy electromagnetic waves. X-rays are high frequency and high energy electromagnetic waves. 10. The wavelength of an electromagnetic wave C) decreases with increasing frequency. 11. The frequency of a light wave C) decreases with increasing wavelength. 12. The energy of a light wave B) increases with increasing frequency. 13. The speed of light A) is fastest in a vacuum. 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? B) Because radio waves have less energy, so they will not damage your skin the way UV rays do. 15. The sun emits em radiation C) across the entire spectrum, but most of the energy is emitted in the visible range of frequencies. 16. How are photons created? B) A vibrating electron will emit a packet of pure energy. This quantum of energy is a photon. 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, 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. 19. Light transmission occurs as C) photons are absorbed and reemitted, but it's not the same photon over and over. 20. Steel is opaque to visible light because 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. 21. The windshield of your car is E) transparent to visible, but opaque to UV and IR frequencies of radiation. 22. When infrared light strikes a pane of glass, C) it is absorbed, causing the entire glass molecule to vibrate, and the energy is dissipated as heat. 23. Ed Buckner says it's going to be 94° by noon. You have two clean t-shirts left, one white and one black, and you know you will have to spend some time outside. B) Wear the white one, since it will reflect more sunlight. 24. What is an additive primary color of light? E) The additive primary colors can be combined to make white light. 25. The additive primary colors of light D) are red, green, and blue. 26. What is a subtractive primary color? C) A color formed by subtracting one color from white light: white - blue = yellow. 27. Two complementary colors of light A) combine to make white. 28. Which of the following pairs are not complementary colors of light? D) Purple and orange. 29. When mixing colors of light, A) red + green = yellow.. 30. When mixing colors of paint, C) yellow + blue = green. 31. Why don't you get the same results when you mix pigments as when you mix photons? B) Because paint pigments are designed to absorb certain frequencies of light. 32. To reproduce the color photos in your textbook, the printer C) uses cyan, magenta, yellow, and black ink. 33. A blue light shines on a fuschia blossom (which is magenta colored). There are no other sources of light. E) The flower looks blue, since magenta = red + blue. Blue is reflected, but there is no red to reflect. 34. A red light shines on a blue shirt. C) No, the shirt reflects blue and absorbs red. It would look black, since there is no blue to reflect. 35. Words in yellow ink are written on a white page. A red light shines on the paper, and there are no other sources of light. E) Page and ink both appear red because they both reflect all the red light that strikes. 36. The sky is blue because C) blue light from the sun is scattered more by the atmosphere than red light. 37. If the molecules in the sky scattered low-frequency light more than high-frequency light, C) the noon sky would appear reddish-orange, while sunsets would appear blue. 38. Sunsets appear reddish-orange because A) the atmosphere, with dust and pollution, efficiently scatters the higher frequency blue light.