1. 4.4 Concave and Convex Mirrors

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

3. Uses of concave mirrors

4. 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

5. 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

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

7. 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

8. Focal point

9. 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

10. 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

11. C F
Original object

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

13. C F

14. 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

15. C F
L: _____________ O: _____________ S: ___________ T: _________
closer
inverted
smaller
real