Convex Lens Lab

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Purpose

To study the images formed by candlelight passing through a convex lens when the candle (object) is placed at 5 different distances from the lens.

Terms

1. convex lens
2. focal length
3. object distance (d_o)
4. image distance (d_i)
5. real image
6. virtual image

Procedure

1. Find the focal length of your lens by letting light coming from the hallway (far away) pass over your shoulder, through the lens, and onto a screen. Focus the image on the screen and measure the focal length of your lens.
2. Place the candle at each of the object distances below, and move the screen until you get a clear image of the candle on the screen.
3. Record the object distance in cm, the image distance, and whether the image is upright or inverted, real or virtual, and larger or smaller than the object itself.
4. If you cannot focus a clear image on the screen, the image is either virtual or there is no image formed at all. If the image is virtual, you may look back through the lens at the candle and see a clear enlarged image of the candle.

   Focal length of your lens: f = __________________ cm

   Place candle at	Object distance (do)	Image distance (di)	real or virtual?	upright or inverted?	smaller, larger, same size?
   do > 2f
   do = 2f
   2f > do > f
   do = f
   do < f

   
   
5. Using a ruler and graph paper, draw the ray diagrams to scale for each of the cases above, as demonstrated in class. Be sure to label the object, image, and all distances.