We do not clean natural ponds or lakes, whereas an aquarium or a swimming pool needs to be cleaned regularly. Why?
Natural ponds and lakes have a self-cleaning system where natural processes such as filtration, sedimentation, and biological processes help maintain water quality. However, aquariums and swimming pools are enclosed and do not have these natural processes, which is why they require regular cleaning and maintenance to prevent the accumulation of waste and maintain clean water.
| Case No. | Lens | Focal Length | Object Distance |
|---|---|---|---|
| 1 | \(A\) | 50 cm | 25 cm |
| 2 | B | 20 cm | 60 cm |
| 3 | C | 15 cm | 30 cm |
Consider the following food chain: Grass → Grasshopper → Frog → Snake → Eagle If the amount of energy available at third trophic level is 50 kJ, the available energy at the producer level was:
| Case No. | Lens | Focal Length | Object Distance |
|---|---|---|---|
| 1 | \(A\) | 50 cm | 25 cm |
| 2 | B | 20 cm | 60 cm |
| 3 | C | 15 cm | 30 cm |