Lenses

Some folks worked with lenses today, either in lecture or in lab, while others toodled through the basics of refraction.

B and F Blocks took time to get a general understanding of the phenomenon of refraction and how a material's index of refraction impacts the speed, wavelength and path of travel for a ray of light. We linked refraction and index of refraction to dispersion of light by prisms and relied on the law of refraction and Snell's Law to put some actual numbers to our general descriptions. On Monday, we'll move onto lenses, which F Block investigated yesterday and B Block will explore next Wednesday.

C Block started their work on lenses today. We defined what is and isn't a lens and investigated image formation by both converging and diverging lenses. With those ideas in mind, we moved to better describe image formation through the use of ray diagrams. Like I said in class, I wont' ask you to craft a ray diagram for a diverging lens or for a converging lens when it is making a virtual image. However, you should be able to draw one for a converging lens making a real image, as we practiced. Tonight's homework will let you start to examine the relationship between object placement and type, size and position of image and we'll throw the more precise calculations into the mix on Monday.

E Block worked on their Image Formation by Lenses lab, testing both converging and diverging lenses. The converging lens gave you nice, real images that you caught on a screen and let you form a virtual image that you had to look through the lens to see. The diverging lens only makes virtual images, but you could at least use the divergence of the rays from the laser pointer to back-calculate the focal length of the lens. We'll go over this lab on Monday before moving to a more in-depth treatment of lenses.