1. 02/06/2016 Lenses and Images LO: to be able to describe images formed by different types of lenses Starter: make a list of any items you can think of that use lenses

2. 02/06/2016 Lenses are used to refract light to produce images e.g. the lens in the eye is used to focus what we see:

3. Set up the ray boxes and investigate what each of the different lenses do to the light rays. Think about what you can change each time, hint, not just the lens! Can you identify any rules for different lenses? Draw a ray diagram to show what happens to the rays from each type of lens. (Diagrams must be drawn precisely using a sharp pencil and ruler) 02/06/2016

4. Converging and diverging lenses CONVERGING (Convex) Thickest at the centre DIVERGING (Concave) Thinnest at the centre

5. 02/06/2016 Ray diagrams for lenses 1 The rays of light are refracted INWARDS and meet at the focus, F. The image formed is REAL – in other words, it can be seen on a screen The rays of light are refracted OUTWARDS. A VIRTUAL image is formed – in other words, the image doesn’t actually exist F F The point where the rays meet on both is the principle focus. The distance from the centre of the lens to the principle focus is the focal length.

6. What are the different types of lenses used for? Converging: Magnifying glasses Camera lenses Diverging: Lenses to correct short sightedness. 02/06/2016

7. Types of image on a converging lens 02/06/2016

8. Magnification “Magnification” clearly means how much an image is bigger or smaller then the object: Magnification = Image height Object height If the image is larger than the object the magnification is greater than 1. If the image is smaller than the object the magnification is less than 1. e.g. the height of an imaged produced is 1.2cm and the original object height is 3cm. Calculate the magnification.

9. Plenary Design a simple experiment that will allow you to find the focal point of a converging lens. Think about variables and precise drawings of ray diagrams. 02/06/2016