Explain with reason that when sunlight is focused on a piece of paper ...
Why does sunlight focused on a piece of paper with the help of a convex lens burn?
Converging Effect of Convex Lens
A convex lens is a type of lens that converges the light rays that pass through it. When sunlight passes through a convex lens, it converges at a point called the focal point. This converging effect of the convex lens is why the paper burns.
Concentration of Energy
When sunlight is focused on a small area of the paper, the energy of the light is concentrated in that area. This high concentration of energy causes the paper to heat up. If the concentration of energy is high enough, the paper may even catch fire.
Temperature Increase
As the paper heats up, its temperature increases. The temperature increase is due to the absorption of the energy from the sunlight. The temperature increase can cause the paper to ignite and burn.
Combustibility of Paper
Paper is made from cellulose fibers, which are combustible. When the paper is heated to a certain temperature, the cellulose fibers break down, and the paper ignites. The temperature increase caused by the focused sunlight can cause the cellulose fibers in the paper to break down and ignite, leading to the burning of the paper.
Conclusion
In conclusion, when sunlight is focused on a piece of paper with the help of a convex lens, the paper will burn because of the converging effect of the lens, concentration of energy, temperature increase, and combustibility of the paper.