1. Introduction: Why the Same Mirror Gives Two Different Faces
Take the steel spoon again — the one you met in the last lesson. Hold the caved-in side close to your eye. Your face is big and upright. Now stretch your arm out and look again. Your face has flipped upside down, and it is smaller.
Same mirror. Same face. Two completely different images. Nothing about the spoon changed — only how far your face was from it.
Stop scrolling. Try it in your head before reading on: what is the one thing that decided whether your face stayed upright or flipped over?
The answer is distance. Where you place the object in front of a concave mirror decides everything about the image — whether it is big or small, upright or flipped, in front of the mirror or behind it.
But you cannot guess these things. There is a clean, exact way to find the image for any object position: you draw a ray diagram. You send out two known rays of light from the object, follow how the mirror bounces them, and see where they meet. Where they cross is where the image sits.
This lesson teaches you to draw that diagram for a concave mirror — and to read it, so a picture tells you the size, the position, and whether the image is real or upside down. Get this, and every concave-mirror question after it becomes a picture you can draw from memory.