An agricultural researcher investigated how light intensity affects the photosynthetic rate of Cabomba caroliniana (fanwort) by measuring the rate of oxygen release (in bubbles per minute) at various distances from a high-power LED light source.
The table below shows the results of their investigation:
| Distance from the LED source in cm\text{cm}cm | Rate of oxygen release in bubbles per minute | Light intensity in arbitrary units (a.u.\text{a.u.}a.u.) |
|---|---|---|
| 10 | 92 | 0.01000 |
| 16 | 61 | 0.00391 |
| 25 | 32 | 0.00160 |
| 40 | 8 | ? |
Calculate the light intensity at a distance of 40 cm from the light source.
State the inverse square law equation in your answer and show your working.
