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CURVED MIRRORS. Formation. A curved is formed by cutting out a circular piece of glass from a hollow glass sphere and silvering the outside or inside. C is called the centre of sphere is called the centre of curvature of the mirror. Mirror Terms.
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Formation • A curved is formed by cutting out a circular piece of glass from a hollow glass sphere and silvering the outside or inside. C is called the centre of sphere is called the centre of curvature of the mirror
Mirror Terms • C the centre of the sphere is called the centre of curvature of the mirror • P is the centre of the mirror • An imaginary line drawn passing through C and P is called the principal axis of the mirror.
Concave Mirror • A beam of light parallel to the principal axis is brought to a focus after reflection from a concave mirror. • The focal point is called the principal focus F.
Concave Mirror The focal length is the distance between the centre of the mirror and the principal focus
Convex Mirror • Light rays parallel to the principal axis reflects from the mirror so that they appear to be coming from a point behind the mirror • The apparent focal point is called the principal focus F
Convex Mirror • The focal length is the distance between the centre of the mirror and the apparent focal point • Called a virtual focus
Concave Mirrors • How can we predict the nature and position of the image formed by a concave mirror?
Ray Tracing-Image formation • 3 rays are used to find the position and nature of the image formed by a mirror.
Ray Tracing-Image formation • A ray parallel to the principal axis will pass through the principal focus • A ray passing through the focus will travel parallel to the principal focus • A ray through C will reflect back through C
Image formation by Concave Mirror • Draw vertical line representing the mirror. • Draw a horizontal line through the centre of the mirror representing the principal axis. • Place a dot on the horizontal line to represent F, the principal focus a distance f from mirror centre P.
Image formation by Concave Mirror • Place a second dot at a point on the horizontal line representing C the centre of curvature, 2f from P. • Place the object at C • From the head of the object draw a ray parallel to the principal axis • From the head of the object draw a ray passing through F that will travel parallel to the principal axis after reflection
Extend the reflected rays until they intersect • Where these rays intersect the head of the image will be formed • If a screen is placed at this point the image will form on it. • The image will be real, same size as the object, inverted and at C.