1. How do different lenses affect the image we see.
Starter: how do glasses help to correct long and short sighted vision?

2. Key words
Lens – creates an image by refracting light

3. Converging lenses
Or Principal focus

4. Drawing converging lenses
Rules for drawing ray diagrams.
Do 2 minimum but 3 is better.
Describe the nature of the images using the following words. (The image is the other side of the lens.)
inverted/upright, magnified/diminished, real/virtual.

5. Diverging lenses
Rays appear to come from the principal focus. Use to correct short sight.. Can you work out how?

6. Real vs Virtual Images
A real image is formed by a converging lens. The object is further away than the principal focus. It is formed where light rays meet.
Virtual Image – formed where imaginary rays cross – ( think of a mirror, your image always looks as far away from the mirror as you are because light rays do not converge.)

7. Magnification To work out the magnification… Image Height
Object height
Image > object means magnification will be >1

8. Task
Complete the GCSE Question 2.1
A i, ii , iii and iv

9. Section 2: using Lenses Real Images by Converging lenses.
Ray 1: refracts through F because it is parallel to Principal Axis
Ray 2: passes through the centre of the lens – no change in direction
This line is the principal axis
Ray 3: passes through F the principal focus before the lens. So it is refracted to become parallel. 1 2
This is a REAL image. It is the other side of the lens to the object. 3

10. Cameras A converging lens is used to make a REAL image on a film.
The lens position is altered to focus the image.
Far away : distance from the lens to film = focal length of lens.
Close: the closer you are, the larger the distance from lens to film.

11. Virtual Images Converging Lens
Object is BETWEEN lens and principal focus.
Image is formed on the SAME side of the lens as the object.
Upright, large image.

12. Virtual Images Diverging Lens
Image from a diverging lens is ALWAYS virtual , upright and smaller than the object.