Video narration
Have you ever wondered where parallel rays go after reflecting from a concave mirror? Think of the inward-curved side of a spoon: it can reflect light inward. A concave mirror does something similar in a clear, predictable way. Imagine several light rays traveling side by side, all parallel to the mirror's principal axis-the straight reference line through the mirror. They move toward the curved reflecting surface. What happens next is the important part: after reflection, the rays turn inward and come together. To converge simply means to meet. These reflected parallel rays meet at one specific point on the principal axis. That point is not just any place on the mirror or along the line. It has a special name: the principal focus. So, where do the parallel rays go? They meet at one point on the principal axis-the principal focus of the concave mirror.