Light Phenomenon Make-up Lab To be completed in your notebook In class groups were given one of these experiments to investigate. Each group then demonstrated the experiment to the class, explained what they saw and answered the questions. Watch the videos below to answer the questions. Beads & Shirts: Watch this video of a bunch of beads or this video of beads and a T-shirt. The T-shirt should be white with black and the beads should appear clear when they are not in direct sunlight. 1. There was no color change until the beads and T-shirt were in direct sunlight. What causes the change in the T-shirt and beads? How could you determine this for sure? Speed of light: Using the speed of light, calculate the distance light travels in one nanosecond. Review pg. 437438. 2. Scientists often use a generalized rule “Light travels one foot in one nanosecond.” Is this an accurate rule? Peacock Feather: Watch this video on peacock feathers, this one under a microscope and this Veritasium video. Read pg. 523. 3. How is it that a single material like a peacock feather can appear to be many different colors depending on your viewpoint? Filters: Read pg. 443-444. Watch this video about polarizers, 4. You experimented with materials that are called linear polarizers. Explain how two linear polarizers that are transparent can become opaque. 3D Glasses: This video looking through one pair of 3D glasses at another pair of glasses shows one lens being blacked out by another. Read pg. 443-444. 5. You experimented with 3D glasses that polarized in different directions. Why did that lens black out your partner’s and not the other side? How does it relate to which eye you closed? Black Lines & Rainbow Lights: This demonstration requires no material other than your own fingers. Hold your index and middle fingers close to each other, leaving a small slit between them about 1 mm in width. Look through the slit into a source of light such as the window or a lamp. You will need to look with one eye (so close the other) up close to the slit. It helps to hold your fingers parallel to the ground as shown.

Watch this video about diffraction gratings. Read pg. 439 and pg. 427. 6. How are colors made from white light with the use of diffraction gratings but no colored filters? Optical Fiber: Watch this video about fiber optics. Refer to the Figure 18-4 on pg. 490. 7. Explain how light can travel along a curved path to exit the end of the fiber. Penny Trick: Watch this video about a penny in a cup with water added. 8. Explain how the reflected light off the penny can travel a non-straight path to your eye once water was added when it was originally beyond view.