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Unit 8 – Concave Spherical Mirror C = center of curvature F = focal point f = focal length = ½ the radius of curvature = R/2 p = object distance q = image distance
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Unit 8 – Curved Mirrors
Unit 8 – Concave Spherical Mirror
Concave spherical mirror: a mirror whose reflecting surface is a segment of the inside of a sphere.◦How an image appears depends upon R, the
radius of curvature.◦Radius of curvature is the distance from C,
the center of curvature.
Unit 8 – Concave Spherical Mirror
C = center of curvatureF = focal pointf = focal length = ½ the radius of
curvature = R/2p = object distanceq = image distance
Unit 8 – Concave Spherical Mirror
Image location can be predicted with the mirror equation:
Unit 8 – Concave Spherical Mirror
Example:When an object is placed 30.0 cm in front of a concave mirror, a real image is formed 60.0cm from the mirror’s surface. Find the focal length. (20 cm)
Unit 8 – Concave Spherical Mirror
For a concave mirror, the type of image formed depends on the position of the object
Unit 8 – Concave Spherical Mirror
Rules for ray diagrams:
Ray Line drawn from object to mirror
Line drawn from mirror to image after reflection
1 Parallel to principal axis
Through focal point F
2 Through focal point F
Parallel to principal axis
3 Through center of curvature C
Back along itself through C
Unit 8 – Concave Spherical Mirror
Unit 8 – Concave Spherical Mirror
Unit 8 – Concave Spherical Mirror
Unit 8 – Concave Spherical Mirror
1)Is the image on the SAME or OPPOSITE side of the mirror as the object?◦Same, therefore it is a REAL IMAGE.
2)Is the image ENLARGED or REDUCED?3)Is the image INVERTED or RIGHT SIDE
UP?
Unit 8 – Concave Spherical Mirror
Unit 8 – Concave Spherical Mirror
When the object is at infinity:
Unit 8 – Concave Spherical Mirror
When the object is between infinity and center of curvature:
Unit 8 – Concave Spherical Mirror
When the object is at center of curvature:
Unit 8 – Concave Spherical Mirror
When the object is between center of curvature and focal point:
Unit 8 – Concave Spherical Mirror
When the object is at focal point:
Unit 8 – Concave Spherical Mirror
When the object is between focal point and mirror:
Unit 8 – Concave Spherical Mirror
Magnification relates image and object sizes
Unit 8 – Concave Spherical Mirror
Example:A concave spherical mirror has a focal length of 10.0 cm. Locate the image of a pencil that is placed upright 30.0 cm from the mirror. Find the magnification of the image. Draw a ray diagram to confirm your answer. (q = 15 cm, M = -0.50)
Unit 8 – Concave Spherical Mirror
Homework:◦Worksheet: Concave Mirrors
