P. Sci. Unit 7 Worksheet. Key

Part A.

  1. Which property of light is not explained by the wave model of light? Blue light can knock electrons off a plate but red light cannot
  2. The particle model of light explains how light can travel through empty space without a medium
  3. The amount of energy in a photon of light is proportional to thefrequency of the corresponding light wave
  4. The rate at which light energy flows through a given area of space is referred to as its intensity
  5. Which type of electromagnetic waves has slightly longer wavelengths than red light?infrared
  6. Which type of waves has wavelengths longer than microwaves? Radio waves
  7. Which type of electromagnetic waves has the highest frequency? Gamma rays
  8. Which type of electromagnetic radiation is used to kill cancer cells? Gamma rays
  9. Short-range radar works by sending a signal out from a control tower that is reflected off a plane back to the control tower
  10. The law of reflection states that when light rays reflect off a surface the angle of incidence equals the angle of reflection
  11. An image that results from an apparent path of light rays is called a virtual image
  12. You look at a red tulip, with green leaves, under green light. What would you see? A black flower with green leaves
  13. The color that an object appears to be depends on thewavelengths of light that the object reflects
  14. A virtual image caused by reflection of light in the atmosphere is called a mirage
  15. Light rays that pass through a lens change direction because they are refracted
  1. Which drawing illustrates the law of reflection? c
  2. The two most common models of light describe it as a wave or as a stream of _particles_
  3. In the particle model of light, individual "packets" of light are called _photons_
  4. The energy of light is proportional to the __frequency_ of the corresponding _light wave_.
  5. The amount of light that illuminates a given surface area is referred to as _intensity_.
  6. In a vacuum, all light travels at the same speed, which is _3 X 108 m/s or 186000 mi/s_
  7. All possible kinds of light, at all energies, frequencies, and wavelengths, make up the _electromagnetic spectrum_
  8. The electromagnetic waves with the highest energy and shortest wavelengths are classified as _gamma rays_
  9. _Microwaves_ are used for cooking as well as for communication
  10. A(n) _infrared_ sensor can be used to measure the heat that objects radiate
  11. The theoretical line perpendicular to the surface where light hits a mirror is called the _normal_
  12. The law of reflection states that the angle of _incidence_ is the same as the angle of _reflection_
  13. The image that you see in a mirror that results from the apparent path of light rays is called a(n) _virtual_ image
  14. In a(n) __real_ image, light rays really exist at the point where the image appears
  15. An object looks red if it _reflects_ red light and _absorbs_ all other colors
  16. Light may bend when it changes mediums because _the speed of light_ is different in each medium
  17. Light inside a fiber optic cable bounces off the walls of the fiber because of _total internal_ reflection
  18. A lens that bends light inward is called a(n) _converging_ lens
  19. A lens that bends light outward is called a(n) _diverging_ lens
  20. What does it mean to say that light can be modeled as both a wave and particle? Explain the implications for scientific theory. Scientific theories are successful to the extent that they explain observations. Some observations are best explained by a wave model of light. Other observations are best explained by a particle model. Therefore, both models are currently accepted as correct and light is considered to have a dual nature
  21. Why do scientists use a third model of light, the light ray, in addition to the wave and particle models? How are the three models connected?The light ray, an imaginary straight line that shows how light travels, is a useful tool for describing the way we experience light in everyday life. It is the same as the direction of wave travel in the wave model or the path of photons in the particle model
  22. Explain how rainbows are formed. When sunlight strikes a water droplet in the air, the light is dispersed into different colors as it passes from the air into the droplet. Some of the light reflects off the back surface of the droplet, by means of total internal reflection. It disperses further when it passes out of the droplet. When the light leaves the droplet, we see the different colors of light as a rainbow.