1. Starter (5 mins): Draw ray diagrams
an object is standing in front of a convex mirror.
an object is standing 5 cm away from a concave mirror with the radius of 6 cm.
an object is standing 2 cm away from a concave mirror with the radius of 6 cm.

2. P = pole , pa = principal axis F P r pa f
P = pole , pa = principal axis
C = centre of curvature r = radius of curvature
F = Focal point or focus f = focal length
f = r / 2

3. Descarte’s Formula Newton’s Formula
and
Newton’s Formula
(with mirrors)

4. Descartes’ Formula (with Mirrors)
f = focal length
di = distance between image and mirror
do = distance between object and mirror
Note:
f is negative if the mirror is convex
di is negative if the image is virtual

5. Example:
Find the position and the nature of the image of an object located 40 m in front of a concave mirror with the radius of curvature 64 m.

6. Magnification Factor m = magnification factor hi = height of the image
ho = height of the object
Remember:
m < 1 if the image is diminished
m > 1 if the image is enlarged

7. Example:
An object 7 m high is placed 15 m from a convex mirror of radius 45 m. Find the position, the nature AND the height of the image.

8. Newton’s Formula (with Mirrors)
Si = distance between image and focus
So = distance between object and focus
Note:
Si and So are always positive – which means you can not tell which side of the mirror the image/object is.

9. Example:
An object 7m high is placed 15m from a convex mirror of radius 45m. Find the position and the nature of the image.

10. Magnification Factor m = magnification factor hi = height of the image
ho = height of the object
Remember:
m < 1 if the image is diminished
m > 1 if the image is enlarged

11. Example:
An object 6m high is placed 30m in front of a convex mirror of focal length 40m. Find the position, nature and size of the image formed.

13. Mirrors Formulae Worksheet
Homework Booklet: MIRRORS (five questions)
Textbook: Activity 5B