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Discover the world of mirrors - from plane to concave and convex mirrors; understand real vs. virtual images, lens/mirror equations, and image defects in concave mirrors. Explore spherical aberration and learn to draw images with precision.
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18.1 Mirrors • A. Objects and Images in Plane Mirrors. • B. Concave Mirrors. • C. Convex Mirrors
A. Objects and images in Plane Mirrors. • 1. A plane mirror is a flat, smooth surface from which light is reflected by regular reflection. • a. An object is a source of spreading or diverging light rays. • b. The point at which the source appears to be coming from is called the image. • c. A virtual image is one where the rays do not actually converge.
B. Concave mirrors • 1. A concave or “caved in” mirror reflects light from its inner surface. • 2. Real vs. Virtual images. • 3. Real images formed by concave mirrors. • 4. Lens/Mirror equation. • 1/f = 1/di + 1/do
5. Magnification • m = hi/ho • m = -di/do • Describing a real image • Virtual images formed by concave mirrors • Image defects in concave mirrors • Spherical aberration
C. Convex Mirrors • A convex mirror is a spherical mirror that reflects light from its outer surface. • Focal length of a convex mirror is negative • All images formed are virtual images.
PSS • 1. Choose a scale for your drawing that is approximately the width of your paper. • Locate the image and object locations relative to the mirror. • Choose a scale such that the larger distance is 15 to 20 cm on your paper. • Let 1 cm on the paper represent 1, 2, 4, 5, or 10 actual centimeters.
C f • Draw the principle axis • Draw a vertical line where the principal axis touches the mirror. If the focal point is known, indicate its position on the principal axis.
O1 C f • Draw the object and label its top O1 • Choose a scale for the object that is different than that of the overall drawing because otherwise it may be too small to be seen.
O1 Ray 1 C f • Draw ray 1, the parallel ray. Ray 1 is parallel to the principal axis. All parallel ray to the principal axis are reflected through the focal point.
O1 Ray 1 Ray 2 C f • Draw ray 2, the focus ray. It passes through the focal point, f, on its way to the mirror and is reflected back parallel to the principal axis.
O1 Ray 1 Object Ray 2 Image C f I1 • The image is located where the two rays intersect after reflection. Draw a vertical line from I1 to the principal axis to represent the image.
O O 1 1 Ray 1 Ray 1 Ray 1 Ray 1 Ray 1 Ray 3 Ray 2 Ray 2 Ray 2 Ray 2 Ray 2 Object Object Image Image Image C C C f f f C C I I I I 1 1 1 1 • A third ray may be drawn from the objects top to the center of the mirror which will reflect at the same angle at which it is incident.
Homework • Chapter 18 practice problems 1 – 8.