Chapter 26 Image Formation by Mirrors and Lenses
Chapter 26 Image Formation by Mirrors and Lenses (Geometric Optics for Curved Mirrors)
Curved mirrors
Curved Mirrors Concave mirror Converging mirror Positive mirror Convex mirror Diverging mirror Negative mirror
Terminology
Symbols Converging Mirror = Concave Mirror Diverging Mirror = Convex Mirror
Only one focal point for curved mirrors A lens has two focal points (one on each side of the lens), but a curved mirror only has one focal point. It is important to remember where they are. Concave Mirrors: F in front of the mirror Convex Mirrors: F behind the mirror
Concave Mirror Rules F Rules: 1. Rays parallel to axis Reflect through focal point 2. Rays through focal point Reflect parallel to axis 3. Rays through the center Reflect with equal angle Really the same rules as converging lens
Convex Mirror Rules: 1. Rays parallel to axis Reflect through focal point 2. Rays through focal point F Reflect parallel to axis 3. Rays through the center Reflect with equal angle Really the same rules as diverging lens
Summary
Lens Equation applies f is positive for concave mirror f is negative for convex mirror i is positive if image is in front of the mirror i is negative if image is behind the mirror
Concave mirror 1
Concave mirror 2
Concave mirror 3
Concave mirror 4
Concave mirror case 1 & 4
Convex mirror Find the image F Virtual image
Convex mirror For convex mirror, the image is always virtual and upright, no matter where the object is.
Convex mirror
Confusing signs Converging Lens Diverging Lens Converging Mirror Diverging Mirror Other name Convex Lens Concave Mirror Convex Mirror f + - i when image is on the left - - + + i when image is on the right + + - -
Summary Both equations are true for lens and mirrors, but you have to be very careful about the signs!
Camera
The eye
Nearsighted Eye
Farsighted eye
Microscope
Telescope
Reflecting Telescope
IQ question A piece of glass is placed above the words “LEAD OXIDE”. LEAD appears inverted, but not oxide. Explain.
- Slides: 28