4 4 Concave and Convex Mirrors Concave Mirrors

4. 4 Concave and Convex Mirrors

Concave • Mirrors that have a curved side where the reflective surface is on the “caved in” face of the mirror

Uses of concave mirrors

Concave mirror terms • Principal axis – a line drawn through the centre of the circle Principal axis Vertex (v) – the point where the principal axis meet the mirror

Concave mirror terms • Centre of curvature (C) – the centre of the sphere that the mirror fits on Radius of Curvature – the distance from C to the mirror C

Concave mirror terms • Focal point (F)– exactly halfway between the centre and the mirror Focal length (f) – the distance from F to the mirror Principal axis C F f

Concave mirror terms • All light rays that hit the surface of the mirror are parallel to the principal axis and reflect back through the focal point

Focal point

Drawing Ray diagrams to Locate Images • The type of image produced by a concave mirror will change depending on the location of the object • For example, if the object is: – Beyond C – Between C and F – Between F and the mirror • Each situation will create a different set of image characteristics

Step 1 • Draw a straight line behind the mirror through the vertex • Draw an incident ray parallel to the principal axis that reflects through the focal point

Original object C F

Step 2 • Draw an incident ray through the focal point that reflects parallel to the principal axis

C F

Step 3 • Draw an incident ray through the centre of curvature that will reflect straight back through the centre of curvature • Describe the characteristics of the image

C F inverted L: _______ closer O: _______ S: ______ smaller T: _____ real