The Inverse Square Law
The relationship between light intensity and distance is not linear; it follows the inverse square law.
If you double the distance from a light source, how much does the light intensity drop?
What is The Inverse Square Law?
"The inverse square law states that the intensity of light is inversely proportional to the square of the distance from the source."
Which statement accurately describes inverse square laws at a GCSE level?
A student moves a lamp twice as far from a pondweed plant. What happens to the light intensity?
Why is the inverse square law useful in photosynthesis experiments?
If the distance between a lamp and pondweed doubles, what happens to the light intensity reaching the pondweed?
Calculations
Light Intensity ∝ 1 / (distance)²
Doubling the distance (2x) reduces intensity to 1/4 (2² = 4).
Tripling the distance (3x) reduces intensity to 1/9 (3² = 9).
If distance increases, light intensity decreases significantly.
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