1. Introduction: The Two Sides of a Steel Spoon
Pick up a steel spoon from your kitchen. The clean, shiny kind you stir tea with. Hold the curved-in side close to your face — the side you eat from. Look at your reflection.
Now slowly move the spoon away from your face, an arm's length out. Watch your face in it the whole time.
Something strange happens. Up close, your face is big and the right way up. Far away, your face flips — it turns upside down.
Now turn the spoon around. Look at the bulged-out back of the spoon. Your face is small, the right way up, and it stays the right way up no matter how far you move it.
Same spoon. Same light. Two completely different behaviours from the two sides.
Stop scrolling. Try it in your head before reading on: why would the two sides of one spoon do such different things to your face?
A flat mirror, which you met in the last section, only ever gives you one kind of image — same size, upright, behind the glass. A curved mirror is far richer. It can shrink you, enlarge you, or flip you. To understand any of it, you first have to learn the names of the parts of a curved mirror and what each one measures. That is this lesson. Get these names solid now — every numerical problem on mirrors uses them.