; optics
Documents
User Generated
Resources
Learning Center
Your Federal Quarterly Tax Payments are due April 15th

# optics

VIEWS: 4 PAGES: 47

• pg 1
Optics
Chapter 17 & 18
Topics for Optics
• Reflection of Light • Refraction of Light
– Law of Reflection     – Law of refraction
– Plane Mirrors         – Convex lenses
– Concave Mirrors       – Concave lenses
– Convex Mirrors
• Optical Instruments
Law of Reflection
• All mirrors obey the Law of reflection
• The angle of incidence equals the angle of
reflection
Law of Reflection (Cont.)
• It does not matter the shape of the mirror, the
angle of reflection will still equal the angle of
incidence.
Image Types:
•Real or Virtual
•Upright or Inverted
•Reduced or Enlarged
Real or Virtual
• Real: image      • Virtual: image
projected on a     can only be seen
screen             inside the mirror
Upright or Inverted
• Upright: Image is   • Inverted: Image is
oriented the same     oriented the
direction as the      opposite direction
object                as the object
Reduced or Enlarged
• Reduced: image is      • Enlarged: image is
smaller in size then     larger in size then
the object.              the object.
Plane Mirrors
• The image formed by plane
mirrors can only be seen
behind the mirror.
• This is known as a virtual
image.
• Image is the same size as the
object.
• Only the right and left of the
image is changed.
Curved Mirrors
• They can be considered cut outs of a spherical mirror
• Curved mirrors can be either
– concave (making a little cave)
– convex (vexing out in the middle)
Location of Image

• do = distance of object
• di = distance of image
• f = focal length
Concave Mirrors Converge
Rays of Light
Ray Tracing Basics
• All rays parallel to the
principle axis will go
through the focal point.
• The rays are also
reversible, so if they
start at the focal point,
they will hit the mirror
and go parallel to the
principle axis.
Ray Tracing Basics

• C: Center of Curvature
• F: Focal Point (1/2 of C)
Ray One:
Draw a parallel line from the top of the object to the
mirror.
This line should bounce off the mirror and through the
focal point.
Ray Two:
• Draw a line from the top of the object through the
focal point to the mirror.
• This line should bounce off the mirror and go
parallel to the principle axis.
Ray Three:
• Draw a straight line from the top of the object and
through the Center of curvature.
Reviewing the
three rays:
1. Parallel, then
through f.
2. Through f, then
parallel.
3. Straight line through
top of object and C.
Final step: Draw the image where the
3 lines converge…

Make sure the bottom of the image is on the principle axis,
and the top of the image is at the convergence point.
Distant Objects:
• The image of a distant object will
form at the focal point of the concave
mirror and be very very small.
Objects At C:
The Image will be:
• Real               Same location as object
• Inverted
• Same size
Objects Between C and f:
The Image will be:
• Real               Image is located outside C
• Inverted
• Enlarged size
Objects Inside f:
The Image will be:
• Virtual
• Upright
• Enlarged in size
Convex Mirrors Diverge
Rays of Light
Ray Tracing for Convex Mirrors
• Very similar to ray tracing for concave
mirrors, except the object is on the other
side of the mirror than the Center of
curvature and focal point…
Ray One:
Draw a parallel line from the top of the object to the
mirror.
An imaginary line should be drawn from this point to
the focal point.
Ray Two:
• Draw a line from the top of the object to the focal
point on the other side of the mirror, but stop at the
mirror.
• Draw a line parallel to the principle axis from the
point where the previous line hits the mirror.
Ray Three:
• Draw a straight line from the top of the object and to
the Center of curvature.
Reviewing the
three rays:
1. Parallel, then
through f.
2. Through f, then
parallel.
3. Straight line through
top of object and C.
Final step: Draw the image where the
3 lines converge…
Lenses
Converging Lens
Rules For Converging Lenses
1) Any incident ray traveling parallel to the
principal axis of a converging lens will refract
through the lens and travel through the focal
point on the opposite side of the lens.
2) Any incident ray traveling through the focal
point on the way to the lens will refract through
the lens and travel parallel to the principal axis.
3) An incident ray which passes through the center
of the lens will in effect continue in the same
direction that it had when it entered the lens.
Image Formation by Converging Lens
Diverging Lens
Rules For Diverging Lenses
1) Any incident ray traveling parallel to the
principal axis of a diverging lens will refract
through the lens and travel in line with the focal
point (i.e., in a direction such that its extension
will pass through the focal point).
2) Any incident ray traveling towards the focal
point on the way to the lens will refract through
the lens and travel parallel to the principal axis.
3) An incident ray which passes through the center
of the lens will in effect continue in the same
direction that it had when it entered the lens.
Diverging Lens Image Formation

Always Virtual, Smaller, and Right-Side Up
The Human Eye
The Human Eye
Normal Eye Focus
Near-Sighted (Myopia)
Far-Sighted (Hypermetropia)
Astigmatism
• Cornea is oval shaped instead of spherical.
This causes light to focus on two or more
spots.
LASIK

Laser-assisted In Situ Keratomileusis

To top