The working principle of a magnifying glass is based on the focusing effect of a convex lens. When light passes through a convex lens, due to the different curvatures on both sides of the lens, the light refracts inside the lens, causing the light to converge towards the central axis of the lens. When we place an object within the focal length of a magnifying glass, the light emitted by the object refracts through the lens, forming a magnified virtual image on the other side of the lens. The size of this virtual image depends on the focal length of the magnifying glass and the distance from the object to the lens.

As an important teaching tool, magnifying glasses play an important role in education and scientific research. Through a magnifying glass, students can intuitively observe various microscopic phenomena and details, thereby stimulating their interest and curiosity in science. Meanwhile, magnifying glasses also provide scientists with a tool to observe and study the microscopic world, helping them reveal many unknown mysteries in nature.