1. Ray 1. Incident ray parallel to the principal axis
“Ray Tracing – Concave lens” F
Object
Principal axis 1 2
Image
Ray 1. Incident ray parallel to the principal axis
- emerges from the focal point
Ray 2. Incident ray towards the focal point
- emerges parallel to the principal axis
NB: Both emerging rays diverge away from one another – no real image formed
Trace emerging rays backwards to the intersection point to find the image
(Image is upright, diminished & virtual)

2. “Ray Tracing – Concave lens”
Object placed at beyond double the focal length (>2f)
Object
Principal axis F F
Image

3. “Ray Tracing – Concave lens”
Object placed at double the focal length (2f)
Object
Principal axis F F
Image

4. “Ray Tracing – Concave lens”
Object placed between the focal length (f) and double the focal length (2f)
Object
Principal axis F F
Image

5. “Ray Tracing – Concave lens” Object placed at the focal length (f)
Principal axis F
Image F

6. “Ray Tracing – Concave lens”
Object placed between the focal length (f) and pole of mirror
Object
Principal axis F
Image F

7. “Ray Tracing – Concave lens”
Summary Table
Object
position
Image description
Type
Orientation
Size
Magnification
>2f
Virtual
Upright
Diminished
 0.35 2f
 0.40
Between 2f & f
 0.45 f
1/2
Between f & pole
Enlarged
 0.6