CAUTION: Do not look at the Sun directly or through a lens while doing this Activity or otherwise. You may damage your eyes if you do so.
Hold a convex lens in your hand. Direct it towards the Sun.
Focus the light from the Sun on a sheet of paper. Obtain a sharp bright image of the Sun.
Hold the paper and the lens in the same position for a while. Keep observing the paper. What happened? Why? Recall your experience in Activity 10.2.
✅ Answer: The paper begins to burn and may catch fire.
The parallel rays of light from the Sun are converged by the lens at the sharp bright spot on the paper. It generates heat and causes the burning of paper.
In Activity 10.2, we have found a similar observation using a concave mirror.