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Spherical Mirrors Spherical mirror – a section of a sphere of radius R and with a center of curvature C R C Mirror

Spherical Mirrors

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Spherical Mirrors. Spherical mirror – a section of a sphere of radius R and with a center of curvature C. R. C. Mirror. Spherical Mirrors. The radius ( R ) and center of curvature ( C ) of the sphere Principal axis – a line drawn through C to the mirror - PowerPoint PPT Presentation

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Page 1: Spherical Mirrors

Spherical Mirrors

Spherical mirror – a section of a sphere of radius R and with a center of curvature C

R

C

Mirror

Page 2: Spherical Mirrors

Spherical Mirrors

The radius (R) and center of curvature (C) of the sphere Principal axis – a line drawn through C to the mirror Vertex (V) – where the principal axis intersects the mirror The focal point (F) and focal length (f)

R

C

Principal axis

FV

f

Page 3: Spherical Mirrors

Spherical Mirrors

The focal point (f) is halfway between C and V f = R / 2 R = 2f

Page 4: Spherical Mirrors

Concave (converging) Mirror

Images will form along the focal plane from incoming rays not parallel to the

principal plane.

Inside surface of the mirror forms a “cave”

Page 5: Spherical Mirrors

Convex/Diverging Mirror

Incoming rays that are parallel to the principal axis are reflected such that they appear to diverge from the focal point.This gives the viewer an expanded field of view.

Page 6: Spherical Mirrors

Ray Diagrams

The first ray is drawn parallel to the principal axis and is reflected through the focal point (F).

The second ray is drawn through the center of curvature (C), to the mirror surface, and is reflected directly back.

The intersection of these two rays is the position of the image.

Page 7: Spherical Mirrors

Ray Diagrams – Concave Mirror

C < Do

Center of Curvature < Object Distance

Real image is inverted (upside down) and smaller

Ray 1 “ focuses” in on the focal point, F, after hitting the mirror.

Page 8: Spherical Mirrors

Ray Diagrams – Concave Mirror

F < Do < C

Focal Point < Object Distance < Center of Curvature

Real image is inverted (upside down) and larger

Page 9: Spherical Mirrors

Do < F

Object Distance < Focal Point

Virtual image is not inverted (right side up) and larger

Ray Diagrams – Concave Mirror

Page 10: Spherical Mirrors

Image Characteristics

The characteristics of the images can be described in the following manner:

An image may be real or virtual An image may be upright or inverted An image may be larger or smaller than the

object

Section 7.3

Page 11: Spherical Mirrors

Image Characteristics

Real image – an image for which the light rays converge so that an image can be formed on a screen Real images form in front of the mirror where a

screen can be positioned Virtual image – an image for which the light

rays diverge and cannot form on a screen Virtual images form behind or inside the mirror

where the light rays appear to converge A virtual image results when the object is

inside the focal point

Page 12: Spherical Mirrors

Ray Diagrams – Convex Mirror

Always has virtual image that is not inverted (right side up) and smaller

Page 13: Spherical Mirrors

Example – Concave Mirror

An object is placed 25 cm in front of a concave mirror with a radius of curvature of 20 cm. Construct the ray diagram.

Given: C = 20 cm, therefore f = 10 cm

Image Characteristics:Real image, Inverted, Reduced

Image Distance: approximately 17 cm

17 cm

Page 14: Spherical Mirrors

Example – Concave Mirror

An object is placed 15 cm in front of the concave mirror with a radius of curvature of 20 cm. Construct the ray diagram.

Given: C = 20 cm, therefore f = 10 cm

Image Characteristics:Real image, Inverted, Magnified

Image Distance: approximately 30 cm

30 cm