Yes, it is possible to start a fire using a single plane mirror reflecting sunlight. The underlying physics involved is the concentration of sunlight through the process of focusing.
When sunlight falls on a mirror, it undergoes reflection, bouncing off the mirror's surface. A plane mirror reflects light without distorting it, so the reflected light remains parallel to the incident light. However, by angling the mirror appropriately, the reflected light can be directed to a specific point.
To start a fire, you would position the mirror in such a way that it reflects sunlight onto a small focal point or a specific spot. This can be achieved by aligning the mirror at an angle that redirects the parallel rays of light towards a concentrated area.
At the focal point, the intensity of the reflected light becomes highly concentrated, resulting in an increased energy density. This concentrated energy can heat up the material at the focal point, such as a piece of paper, dry leaves, or other flammable objects. As the temperature rises, the material may eventually reach its ignition point, causing it to catch fire.
The ability to start a fire using a single plane mirror and sunlight relies on the principles of optics and the ability to concentrate light energy to a focal point. It is essential to exercise caution when using concentrated sunlight, as it can be extremely intense and potentially hazardous.