2ndSem.-Physics Light and Optics - Instructor LO-Lab#06 Lab #LO6 - Equipment Each station needs the following: 2 Table lamps (#56) 1 Half-meterstick 1 Eye model with screen in normal (middle) position (#57) 1 Light box with radially-slotted pattern (#57) (there should not be an attached support rod - it needs to rest flat on the table top) 1 "#2 Eye chart" (#57) 1 Lens box containing: (#57) [check to be sure all items are present!] 1. a 13-mm aperture 2. 4 spherical lenses (+2.0, +7.0, +20.0, & -1.75) 3. 2 cylindrical lenses (+1.75 & -5.5) Put the following equipment on the equipment table with the optics setup: Stack of paper towels (#36) 3 eye models (#57) setup with screen in back position, each has one +20.0 lens (#57) 3 eye models (#57) setup with screen in front position, each has one +20.0 lens (#57) One extra light box with radially-slotted pattern (#57) Box of extra frosted light bulbs (#57) Mop (315A storage area) In the hallway: Hang up a copy of the Eye Chart (#57) in the hallway with masking tape. Select a welllit position such that the students can stand 20 feet away from the eye chart. Perhaps hang it on the wall near the fire door by Dr. Morgan's office (Ferg 310). Put a long piece of tape on the floor marking 20 feet away from the eye chart. Each floor tile is 9” 9”. Therefore, 20 ‘ = 26.7 tiles. This should be near the stairs. 2ndSem.-Physics Light and Optics - Instructor Equipment at each station: Equipment at the front: LO-Lab#06 2ndSem.-Physics Light and Optics - Instructor LO-Lab#06 Hands-on Application This is typically one of the most popular labs of the semester. It generally works very well. In order to see if images are well focused and to see a bright spot ~4 m away, you must turn off the overhead lights for this lab. Make sure the students have the correct crystalline lens in place for most of the lab. Some students don’t read carefully and they remove that lens. Students will have to share the eye chart. It is usually mounted in the hallway where there is more light. Mark a distance of twenty feet away from the eye charts. Each floor tile is 9” 9”. Therefore, 20 ‘ = 26.7 tiles. Verify that each "George" and "Martha" model is set up correctly. It should have a +20 lens, filled with water, and the retina in the appropriate position. George = retina in forward ("short") position Martha = retina in back ("long") position Equipment Warnings! Watch that the students carefully fill and empty their eye models. Should water be spilled on the floor, make sure it is cleaned up promptly. A wet floor is extremely dangerous, especially for people using crutches or supports. There are paper towels and a mop to assist with clean up if necessary. Make certain that each lab station has the correct selection of lenses at the end of your lab section. Each group should have one, and no more than one, of each of the lenses and apertures. Watch that students don't spill water on the computers! Closing Discussion Ask groups (or the class as a whole) to summarize their findings for the human eye. Ask students to review how the eye model is similar to and how it is different from the human eye. Lab Cleanup Throw away all used paper towels. Make sure there is no water on the hallway floor. Verify that all lab stations have a complete set of lenses/apertures Verify that all Georges and Marthas have been returned to the front table and are ready for the next class. They can stay filled with water if there is a lab immediately following. However, please empty them when they sit over night.