j.m. gabrielse concave (just a part of a sphere)
TRANSCRIPT
J.M. Gabrielse
Concave Mirrors(caved in)
Examples include:• Shaving and makeup
mirrors
• Inside of a metal spoon
J.M. Gabrielse
optical axis
Concave Mirrors(caved in)
•F
Light rays that come in parallel to the optical axis reflect through the focal point.
J.M. Gabrielse
Concave Mirrors
Because concave mirrors are curved inward they reflect light rays in special way: reflected light rays travel toward each other, or converge.
J.M. Gabrielse
principal axis
Concave Mirror (when object is between focal point and mirror)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
J.M. Gabrielse
principal axis
Concave Mirror (when object is between focal point and mirror)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
J.M. Gabrielse
principal axis
Concave Mirror (when object is between focal point and mirror)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
A third ray travels to the vertex and reflects at the same angle.
J.M. Gabrielse
principal axis
Concave Mirror (when object is between focal point and mirror)
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
A third ray travels to the vertex and reflects at the same angle.
A virtual image forms where the sight rays converge.
•F
J.M. Gabrielse
principal axis
Your TurnConcave Mirror
(when object is between focal point and mirror)
•F
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
object
J.M. Gabrielse
principal axis
Your Turn-AnswerConcave Mirror
(when object is between focal point and mirror)
•F
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
object
J.M. Gabrielse
Characteristics of images in Concave Mirrors
(when an object is between the focal point and the mirror)
• S The image is larger than the object.• P The image distance is larger than the object
distance.• O The image is upright.• T The image is virtual (object's image lies behind
the mirror).
J.M. Gabrielse
Concave Mirror(when object is between the focal point and 2 times the
focal point)
•F
•2F
principal axis
The first ray comes in parallel to the principal axis and reflects through the focal point.
J.M. Gabrielse
Concave Mirror(when object is between the focal point and 2 times the
focal point)
•F
•2F
principal axis
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
J.M. Gabrielse
Concave Mirror(when object is between the focal point and 2 times the
focal point)
•F
•2F
principal axis
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
A ray travels to the vertex.
A real image forms where the light rays converge.
J.M. Gabrielse
principal axis
Your TurnConcave Mirror
(when object is between the focal point and 2 times the focal point)
•Fobject
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
•2F
J.M. Gabrielse
principal axis
Your Turn-AnswerConcave Mirror
(when object is between the focal point and 2 times the focal point)
•Fobject
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
•2F
J.M. Gabrielse
Characteristics of Images in Concave Mirrors
(when object is between the focal point and 2 times the focal point)
• S The image is larger than the object.
• P The image distance is larger than the object distance.
• O The image is inverted.
• T The image is real (located in front of mirror)
J.M. Gabrielse
principal axis
Concave Mirror (when object is beyond 2 times the focal point)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
J.M. Gabrielse
principal axis
Concave Mirror (when object is beyond 2 times the focal point)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
J.M. Gabrielse
principal axis
Concave Mirror (when object is beyond 2 times the focal point)
•F
The first ray comes in parallel to the principal axis and reflects through the focal point.
The second ray comes through the focal point and reflects parallel to the principal axis.
A real image forms where the light rays converge.
J.M. Gabrielse
principal axis
Your TurnConcave Mirror
(when object is beyond 2 times the focal point)
•Fobject
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
J.M. Gabrielse
principal axis
Your Turn-Answer(Concave Mirror)
(when object is beyond 2 times the focal point)
•Fobject
concave mirror
• Note: mirrors are thin enough that you just draw a line to represent the mirror• Locate the image of the arrow
J.M. Gabrielse
Characteristics of Images in Concave Mirrors
(when object is beyond 2 times the focal point)
• S The image is smaller than the object.
• P The image distance is smaller than the object distance.
• O The image is inverted.
• T The image is real (located in front of mirror).
J.M. Gabrielse
Interactive Activity
See the effects of moving the object closer to the mirror, first between the center of curvature and the focal point, and then between the focal point and the mirror surface (to form a virtual image):
• http://micro.magnet.fsu.edu/primer/java/mirrors/concavemirrors/index.html
See how moving the object farther away from the center of curvature affects the size of the real image formed by the mirror:
• http://micro.magnet.fsu.edu/primer/java/mirrors/concavemirrors3d/index.html
J.M. Gabrielse
Can You Name Some Other Examples of Concave Mirrors?
Other examples of concave mirrors include:• spotlights, • flashlights, • overhead projectors, • car headlights, and• lighthouses.
J.M. Gabrielse
More Examples
• The largest telescopes all use concave mirrors to collect light because the mirror concentrates the light so effectively.
• Satellite dishes that receive television signals are curved dishes that reflect the microwaves coming from satellites.