Final answer:
To redirect sunlight onto a wall on the same side as a window, a mirror can be used due to its ability to reflect light effectively in a specific direction.
Step-by-step explanation:
To make sunlight fall on a wall on the same side as the window, you can use a mirror to reflect the sunlight onto the wall. Mirrors are effective for redirecting light because they are very smooth surfaces that can reflect light in a single, specific direction. This characteristic is described by the principle that light travels in straight paths when it reflects off smooth surfaces, acting like rays. A good-quality mirror can reflect more than 90% of the light that falls on it, making it an excellent tool for directing sunlight where it is desired.