Download Ch. 18 Mirrors and Lenses

Ch. 18
Mirrors and Lenses
Milbank High School
Sec. 18.1
Mirrors
• Objectives
– Explain how concave, convex, and plane
mirrors form images.
– Locate images using ray diagrams, and
calculate image location and size using
equations.
– Explain the cause of spherical aberration
and how the effect may be overcome.
– Describe uses of parabolic mirrors.
Plane Mirrors
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Plane mirrors
Object
Images
Virtual Image
Concave Mirrors
• Reflects light from its inner “caved in”
surface
• Principal axis
• Focal point
• Focal Length
• Real Images
Concave Mirrors
• Real, inverted images if object is farther
from the mirror than the focal point
Calculations…
di is distance from the image to
the mirror
• Lens/Mirror Equation: d0 is the distance from the object
to the mirror
• Magnification:
f is focal length of the mirror
• Example problem Pg. 422
– Calculating the Real Image Formed by a Concave Mirror
• Example problem Pg. 424
– A Concave Mirror as a Magnifier
Convex Mirrors
• Reflects light from its outer surface,
always diverge
• No real image, upright
• Reduced in size (wide angle mirrors)
Calculations…
• Use same Lens/Mirror Equation
– Focal length is negative
– di is negative (image is behind the mirror)
• Pg. 427 Pr. 6
Sec. 18.2
Lenses
• Objectives
– Describe how real and virtual images are
formed by convex and concave lenses.
– Locate the image with a ray diagram and
find the image location and size using a
mathematical model.
– Define chromatic aberration and explain
how it can be reduced.
– Explain how optical instruments such as
microscopes and telescopes work.
Types of Lenses
• Lens
• Convex lens
• Concave lens
Convex lenses (converging
lenses)
• Produce real, inverted images if the
object is farther from the lens than the
focal point
• If object is closer than the focal point, a
virtual, upright, enlarged image is
formed
Concave Lenses (diverging
lenses)
• Produce virtual, upright, reduced
images
Calculations…
• f is positive for convex lenses
• f is negative for concave lenses
• do is positive on the object side of the
lens
• di is positive on the other side (image
side) of the lens, where images are real
• di is negative on the object side of the
lens where images are virtual
• Ex. Prob. Pg 431
• Ex Prob. 434