1. Lenses General Physics Java Applets

2. Images in Lenses S ize, A ttitude, L ocation, T ype Size –Is the image bigger, smaller or the same size as the object? M = h i h o Attitude –Is the image right side up (upright) or upside down (inverted)?

3. Images in Lenses - Location

6. Images in Lenses Type –Is the image real or virtual?

7. Thin Lens And Magnification Equation 1=1+1fdido1=1+1fdido HiHi HoHo

8. Some Rules Distances to objects are always positive. Distances to real images are always positive and virtual images are always negative. Converging lenses have positive focal lengths. Diverging lenses have negative focal lengths. Heights above the PA are positive, heights below the PA are negative.

9. Sample Problem A pencil 8.0cm high is placed 36.0cm in front of a converging lens with a focal length of 18.0cm. –Find the distance to the image. –The height of the image. –Describe the characteristics of the image.

10. Questions 1.A piece of newspaper with print 2.0cm high is placed 20cm from a diverging lens with a focal length of 12cm. Calculate: a)The distance to the image. [-7.5cm] b)The height of the image. [0.75cm] c)Describe the characteristics of the image. 2.A candle 20cm high is placed behind a converging lens with a focal length of 25cm. If the image of the candle is 30cm from the lens, calculate: a)The distance from the lens to the object. [150cm] b)The height of the image. [-4.0cm] c)Describe the characteristics of the image. 3.A lens with a focal length of -1.5cm is placed 2.9m from a 20cm tall candle. Calculate the height that the candle appears when it is viewed in the lens. [8.6cm] 4.A slide projector has a lens with a focal length of 10.0cm. A slide of a truck is placed 11.0cm from the lens. Calculate the distance the screen should be away from the projector to ensure a clear image is projected. [1.10m]