Lenses Lab

In this lab, we looked at the behavior of light through a magnifying glass which is a double convex lens.
We used a light box which illuminated a pattern on a piece of paper, and placed the magnifying glass at specific distances away from the light box, and had a blank sheet on which to project the image.

Before we could do anything, however, we needed to measure the focal length of our lens. To do this, we went outside and focused the light from the sun onto the ground until the light entering the lens was focused at a single point. The focal length was simply the height above the ground.
The focal length of our magnifying glass was found to be  f = 14 cm +/- 0.5 cm

After that, we placed the light box at various distances (object distance) from the lens, and found the image distance (where the projection on the sheet was most clear) and measured the image height on the sheet. The object height is constant and is simply the height of the printed pattern on the paper on the light source.

Object distance (cm)	Image Distance (cm)	Image Height (cm)	Object height (cm)	Magnification
5*f = 70	22.5	1	3 cm	1/3
4*f = 56	24	1.5		1/2
3*f = 42	28	2		2/3
2*f = 28	43	4.8		1.6
1.5*f = 21	85	12.5		4.2

We then tried to get an image when the light box was only 0.5*f away from the lens. We were unable to get a image to show up on the sheet at any distance. However, we are able to see a very clear virtual image by looking through the lens from any point.