### Geometrical Optics Pre-lab Assignment

In the Geometrical Optics experiment you will examine real and virtual images formed by lenses. Use the simulation here to become more familiar with the image formation process and to answer the questions below.

1. Place the object closer to the converging lens than the focal point is. Describe the image characteristics. What happens to the image when the object is moved even closer to the lens?

2. Now change to a diverging (concave) lens. Describe the image characteristics for this case. What happens to the image when the object is moved closer to the lens?

3. Lenses have two focal points, one on each side of the lens. If an object is placed at the focal point to the left of a diverging lens, where is the image? Compare this to what happens when the object is placed at the focal point to the left of a converging lens. Comment on what you observe.

4. Look carefully at the ray diagrams shown in the simulation. In the simulation, a light ray passing through a lens changes direction once, when the ray reaches the vertical line passing through the middle of a lens. Where does the change of direction happen for a real lens? How many changes in direction occur for a light ray passing through a real lens?