Applied Science - Technology (5A)
Lab 

   
OBJECTIVES:
  • Comparing light from a laser with a flashlight.
  • Exploring other types of electromagnetic waves.

VOCABULARY:

  • crest
  • electromagnetic
  • frequency
  • light
  • trough
  • wavelength
MATERIALS:

Students experiment with light using lasers and flashlights.

BACKGROUND:

Visible light is only a small part of the entire electromagnetic wave spectrum, as shown in the diagram below. In nature, waves differ in frequency and wavelength, however all have the same speed (186,000 miles per second or 296,000 meters per second).

PROCEDURE:

  1. Illustrate the parts of a wave in the electromagnetic spectrum. An electric field radiates from every substance in the form of these waves. Wavelength refers to the distance between crest to crest; frequency refers to the number of times the wave cycles in a given time. The shorter the wavelength, the higher the frequency. The longer the wavelength, the lower the frequency. The waves of the spectrum reflect the difference in frequency.
      
  2. Using the material in the module, give a group of students a flashlight and one prism, quartz, mirror, cube magnifier, convex lens, ulexite, and calcite. Students should shine the light through the items to see what the light does. Have them draw a picture of what they see. The room must be dark in order for the students to observe the phenomena. Repeat the activity with a laser and compare the differences. The laser light is sharper than light from the flashlight. In an upcoming lab, students will look at a laser in more detail. Have students become familiar with the laser and go over the instructions for safety. LASERS ARE NOT TOYS!
       
  3. Conclude that light can be modified by different mediums. Convex lenses will concentrate the light, mirrors will reflect the light. The flashlight will make the quartz shine, but the laser will almost irradiate it. When shown through calcite, the laser will double the light, however the flashlight will not produce any doubling. The laser light will go through the ulexite, but the flashlight will not. This may vary some with the materials and the light source you use. Students will learn more about the laser in the post lab. This lab serves to illustrate that there is a difference between laser light and flashlight light.
      
  4. The answers are dependant on the individual specimens. The key objective is to observe laser and incoherent light.

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