Schottenbauer Publishing

Monday, August 3, 2015

Intensity of Light and Brightness

Conservation begins with efficiency. How bright does a light bulb really need to be? It turns out that the intensity of light is related not only to light bulb construction, but also to distance from the light bulb. Consider the following graph, excerpted from The Science of Energy Efficiency, available from Schottenbauer Publishing.

Discussion Questions
  1. What does the horizontal axis represent? How does this variable affect the graph?
  2. What is the intensity of light near the bulb?
  3. What is the intensity of light at 36 inches? 
  4. Approximately what is the intensity of light at 48 inches?
  5. Assuming a constant velocity of the measurement unit, approximately what is the intensity of light at 12 inches? 24 inches?
  6. Redraw the graph as distance from light bulb (x-axis) versus intensity of light (y-axis).
  7. Is the velocity constant in this graph, or is the probe slightly faster or slower on approach (compared to retreat)?
  8. What is the range of natural distance for using a lightbulb in a typical home? Would this light bulb be sufficient for a reading light?

Over 8,000 graphs from Schottenbauer Publishing provide additional real-life topics for student learning, including sports, transportation, construction, environment, music, entertainment/toys, and general physics. 

Additional Information