calculate - distance and light intensity - Higher only

• What process do plants use to make their own food?

  Photosynthesis
• Why is the food produced by plants important?

  It is important for the plants themselves and for other organisms that feed on them
• What is the relationship between distance and light intensity?

  • Inverse relationship: as distance increases, light intensity decreases
  • Light energy spreads over a wider area with increased distance
• What happens to light energy at twice the distance from a light source?

  It is spread over four times the area
• What is the inverse square law in relation to light intensity?

  Light intensity is inversely proportional to the square of the distance
• How is light intensity calculated in relation to distance?

  Light intensity is proportional to the inverse of $d^{2}$
• What is the calculation for $\frac{1}{d^{2}}$ when the lamp is 10 cm away from the plant?


  $\frac{1}{d^{2}} =$$\frac{1}{10^{2}} =$$0.01$
• What data was collected from the experiment regarding distance and rate of photosynthesis?

  • Distance 10 cm: Rate 120
  • Distance 15 cm: Rate 54
  • Distance 20 cm: Rate 30
  • Distance 25 cm: Rate 17
  • Distance 30 cm: Rate 13
• How do you complete the results table for distance, $\frac{1}{d^{2}}$, and rate?


  • Calculate $\frac{1}{d^{2}}$ for each distance
  • Fill in the corresponding rate of photosynthesis
• What is the relationship between the rate of reaction and $\frac{1}{d^{2}}$ when plotted on a graph?


  The graph is linear
• What does $\frac{1}{d^{2}}$ represent on the x-axis of the graph?


  It represents values of $\frac{1}{d^{2}}$, not light intensity
• What is the relationship between light intensity and $\frac{1}{d^{2}}$ at low light intensities?


  $\frac{1}{d^{2}}$ is proportional to light intensity