unit 8 – curved mirrors. unit 8 – concave spherical mirror concave spherical mirror: a mirror...

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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

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