Light demos turned into expert lab: 1) UV beads and shirt, 2) nanosecond bar double check calculation, 3) peacock feather with explanation sheet? 4) Polarizers together, and 5) glasses, 6) diffraction glasses and fingers, 7) laser & optical fiber, 8) penny demo for refraction Beads & Shirts: You have a bag of beads and a T-shirt. The T-shirt should be white with black and the beads should appear clear. Move them all near a window and observe the changes. Move the materials back out of direct sunlight and observe changes. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: The lights are on in the classroom and yet 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: You have a length of material labeled “nanosecond bar.” Using the speed of light, calculate the length this material should be in order for light to travel its length in one nanosecond. Review pg. 437-438. Discuss with your group your calculated length. Answer this question as you will be demonstrating what you did and explain it to other groups: Scientists often use a generalized rule “Light travels one foot in one nanosecond.” Is this an accurate rule? Peacock Feather: Look carefully at the peacock feather and any other iridescent materials given to you. Try using a magnifying glass as well. Read pg. 523. Discuss with your group what see and what you read. Answer this question as you will be demonstrating what you saw and explain it to other groups: How is it that a single material like a peacock feather can appear to be many different colors depending on your viewpoint? Filters: You have two filters. Look through one at the rest of the room and notice everything looks a bit darker. Stack one filter on top of the other and it should be even darker. Rotate one of the filters by 90 degrees and observe. Keep rotating and see what changes. Read pg. 443-444. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: You experimented with materials that are called linear polarizers. Explain how two linear polarizers that are transparent can become opaque. 3D Glasses: You have at least two pairs of 3D glasses. Put a pair on and have a partner put another pair on. If you look at your partner you will see that they appear darker through the filters in the glasses. Take turns closing one eye while looking at your partner and have them do the same. Read pg. 443-444.

Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: 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. Look at a white light source such as a window or a lamp through the diffraction gratings provided. Read pg. 439 and pg. 427. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: How are colors made from white light with the use of diffraction gratings but no colored filters? Optical Fiber: Shine a laser into one end of the optical fibers provided and observe its path inside the fiber and out the other end. Refer to the Figure 18-4 on pg. 490. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: Explain how light can travel along a curved path to exit the end of the fiber. Penny Trick: Place a coin in the bottom of an empty opaque cup as shown. No move your head down while looking at the coin over the edge of the cup until the coin just disappears from view. Now with your head held in this position, have a partner fill the cup with water and watch the coin come back into view. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: 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.

Beads & Shirts: You have a bag of beads and a T-shirt. The T-shirt should be white with black and the beads should appear clear. Move them all near a window and observe the changes. Move the materials back out of direct sunlight and observe changes. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: The lights are on in the classroom and yet 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: You have a length of material labeled “nanosecond bar.” Using the speed of light, calculate the length this material should be in order for light to travel its length in one nanosecond. Review pg. 437-438. Discuss with your group your calculated length. Answer this question as you will be demonstrating what you did and explain it to other groups: Scientists often use a generalized rule “Light travels one foot in one nanosecond.” Is this an accurate rule?

Peacock Feather: Look carefully at the peacock feather and any other iridescent materials given to you. Try using a magnifying glass as well. Read pg. 523. Discuss with your group what see and what you read. Answer this question as you will be demonstrating what you saw and explain it to other groups: How is it that a single material like a peacock feather can appear to be many different colors depending on your viewpoint?

Filters: You have two filters. Look through one at the rest of the room and notice everything looks a bit darker. Stack one filter on top of the other and it should be even darker. Rotate one of the filters by 90 degrees and observe. Keep rotating and see what changes. Read pg. 443-444. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: You experimented with materials that are called linear polarizers. Explain how two linear polarizers that are transparent can become opaque.

3D Glasses: You have at least two pairs of 3D glasses. Put a pair on and have a partner put another pair on. If you look at your partner you will see that they appear darker through the filters in the glasses. Take turns closing one eye while looking at your partner and have them do the same. Read pg. 443-444. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: 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?

Optical Fiber: Shine a laser into one end of the optical fibers provided and observe its path inside the fiber and out the other end. Refer to the Figure 18-4 on pg. 490. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: Explain how light can travel along a curved path to exit the end of the fiber.

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.

Look at a white light source such as a window or a lamp through the diffraction gratings provided. Read pg. 439 and pg. 427. Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: How are colors made from white light with the use of diffraction gratings but no colored filters?

Penny Trick: Place a coin in the bottom of an empty opaque cup as shown. No move your head down while looking at the coin over the edge of the cup until the coin just disappears from view. Now with your head held in this position, have a partner fill the cup with water and watch the coin come back into view.

Discuss with your group what happened. Answer this question as you will be demonstrating what you saw and explain it to other groups: 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.