Light and Colour - Concave/Convex Mirrors PDF

LIGHT AND COLOUR Shiny smooth surfaces reflect regularly, other surfaces also reflect light but if the surface is rough the light is reflected in all directions. We call this diffuse GIve an example of each: Specular Reflection Diffuse Reflection http://micro.magnet.fsu.edu/primer/java/...

LIGHT AND COLOUR Shiny smooth surfaces reflect regularly, other surfaces also reflect light but if the surface is rough the light is reflected in all directions. We call this diffuse GIve an example of each: Specular Reflection Diffuse Reflection http://micro.magnet.fsu.edu/primer/java/mirrors/concave.html Convex and Concave Mirrors A convex mirror is a diverging mirror. Parallel rays of light are reflected so that they appear to come from the focal point of a convex mirror. A concave mirror is a converging mirror. Parallel rays of light are reflected through the focal point of a concave mirror. Explain one place you have seen a convex mirror.  Uses of Concave Mirrors Used to collect light energy, sound, heat, radiation, radar and TV signals. If you move close to a concave mirror, then you see a magnified image of yourself. This image is upright and virtual as well as magnified. Shaving and make up mirrors  Concave Mirrors Curves inward May be real or virtual image Curved mirrors  Spherical Mirrors This is a ray diagram for finding the focal point of a concave mirror.  Spherical Mirrors We have made the assumption here that the rays do not hit the mirror very far from the principal axis. If they do, the image is blurred; this is called spherical aberration, and can be remedied by using a parabolic mirror instead.  Spherical Mirrors When the Hubble Space Telescope was first launched, its optics were marred by spherical aberration. This was fixed with corrective optics.  Images 4 main characteristics 1) Location-use landmarks i.e. in front or behind mirror, C & f 2) Orientation (upright or inverted) 3) Size (same size, larger than, smaller than) 4)Type (real image or virtual image) For a real object close to the mirror but outside of the center of curvature, the real image is formed between C and f. The image is inverted and smaller than the object. For a real object at C, the real image is formed at C. The image is inverted and the same size as the object. For a real object between C and f, a real image is formed outside of C. The image is inverted and larger than the object. What size image is formed if the real object is placed at the focal point f? For a real object at f, no image is formed. The reflected rays are parallel and never converge. For a real object between f and the mirror, a virtual image is formed behind the mirror. The image is upright and larger than the object.  Convex Mirrors Curves outward Reduces images Virtual images –Use: Rear view mirrors, store security… CAUTION! Objects are closer than they appear!  Convex Mirror Diverging Mirror Center of curvature on side opposite reflecting side of mirror  Convex Mirror Rays leaving mirror will always diverge – A convex mirror will always produce a virtual image that is upright and reduced. Uses – rear view mirror: “objects in mirror are closer than they appear”. – security mirror in stores.  Ray Diagram: Convex Mirror Notice the focal point is behind the mirror Ray Diagram: Convex Mirror  Uses of Convex Mirrors They always produce virtual upright images. The image is always smaller than the object. They are useful when you want a wide field of view – car driving mirrors or shop security.  Concave Mirror Convex Mirror – Curves away from – Curves toward viewer viewer – Diverging – Converging – Produces image that is – Produces real or virtual virtual, upright, images that are reduced magnified or reduced, upright or inverted, depending on distance.