3 Geometrical Optics Pt 3

Light & Optics Unit Becky McCoy

Lesson Title: Geometrical Optics Part 3 Timing: 50 Minutes Target Audience: High School Conceptual Physics Course (9th – 12th grade)

Objectives: Students Will Be Able To: • Identify what happens to light when it enters a new medium. • Draw ray diagrams for light traveling through different mediums. The Teacher Will Be Able To: • Identify students who are struggling to accept the concepts. • Reinforce ray theory ideas. • Provide more opportunities for students to learn

Standards Assessed: New York State, The Physical Setting 4.3 viii. draw ray diagrams to represent the reflection and refraction of waves 4.3 ix. determine empirically the index of refraction of a transparent medium

Misconception(s) Addressed: • • • • • •

Light does not travel. Light does not bounce or reflect. Water/beakers make pencils look broken. Water magnifies objects. Refraction is the bending of waves. In refraction, the characteristics of light change.

Prior Knowledge: Previous lessons and basic knowledge of light and optics. Aim: Investigate what happens to light when it passes through different mediums. Concept Map Vocabulary: • • •

Refraction Snell’s Law Medium of Propagation

Necessary Preparation: COPIES • Lab Worksheets MATERIALS

Light & Optics Unit Becky McCoy • Opaque Cups • Clear plastic cups/beakers • Water • Straws/Pencils • Coils • Oil • Alcohol SET UP • Water in clear cups with straws/pencils should be set for students when they arrive.

Light & Optics Unit Becky McCoy

Lesson Plan

Aim: Investigate what happens to light when it passes through different mediums. Physics Push-Up: Group Broken Pencil Discovery (5 minutes) Students will look at the cups filled with water on their desks/tables (one per group of 4-5 students). They will have a pencil, drinking straw, or some other straight object to place in the water. They should write one sentence explaining why the pencil appears broken. In order to transition, explain that cormorants are birds used by fisherman of East Asia. They are large voracious dark-colored long-necked sea birds with a pouch for holding fish. With their long sharp bills they dive into the water to pierce fish and take the fish back to the fisherman.

Activity: Spear Fishing Birds (10 minutes) Materials: • Opaque Cup • Coin (quarters work well) • Water • Oil • Alcohol Procedure: 1. In your groups, predict whether a cormorant must aim above, below, or directly at a fish in order to pierce it. 2. Assign a viewer (make observations), recorder (record observations), reporter (report observations to the class), and reader (read the activity instructions). 3. Place an opaque cup in front of the group’s viewer, the person should be able to see down the cup but at an angle. 4. Place a coin into the opaque cup and place it until it is out of view. 5. Pour water into the cup until it becomes completely visible. 6. Record the height of the water in centimeters. 7. Repeat the procedure for oil and alcohol. Record the height of each on the data table. Questions to Ask: • Describe what has happened? • What allows you to see the coin? (Introduce the term “refraction”) • Why is it that we did not see the coin until the water, oil, or alcohol were added? • Based on the experiment, where would a cormorant aim? • Does this prove or disprove your hypothesis? • Restate your hypothesis if necessary.

Light & Optics Unit Becky McCoy

Activity Summary: Geometrical Optics (25 minutes) Finish the Geometrical Optics power point. Show students how the object (fish, penny) appear to be in a different location than they are. Allow students time to ask questions and mention other occasions of refraction making activities difficult to complete.

Homework: Cormorant Activity Response (5 minutes) Students should respond to the posed questions for homework in the form of a short essay. Advertising Optical Technology project due next class.

Exit Strategy: Project Check-In (5 minutes) Each student should say which media their advertisement is for and what piece of technology they are proposing to market.

Extension Activity: Practice additional examples of ray diagrams for different mediums.

Assessment: • •

Teacher evaluation of student reactions, questions, and responses during class. Physics Push-Up, homework, and exit strategy responses.

Resources: Tonya Springer-De Caul: http://www.scienceteacherprogram.org/physics/TSpringer03.html Making Sense of Secondary Science by Rosalind Driver Cormorant Fishing: http://en.wikipedia.org/wiki/Cormorant_fishing

Notes & Adaptations:

Light & Optics Unit Becky McCoy Name ____________________________________________________________ Date __________________

Cormorant Lab Worksheet Background Humans have historically exploited cormorants' fishing skills, in China, Japan, and Macedonia, where they have been trained by fishermen. A snare is tied near the base of the bird's throat, which allows the bird only to swallow small fish. When the bird captures and tries to swallow a large fish, the fish is caught in the bird's http://en.wikipedia.org/wiki/File:Cormor ant_chinese.JPG throat. When the bird returns to the fisherman's raft, the fisherman helps the bird to remove the fish from its throat. The method is not as common today, since more efficient methods of catching fish have been developed.

http://www.bbc.co.uk/devon/content/images/20 08/02/18/cormorant_phelps_lowman_465x329. jpg

In Japan, cormorant fishing is called ukai. Traditional forms of ukai can be seen on the Nagara River in the city of Gifu, Gifu Prefecture, where cormorant fishing has continued uninterrupted for 1300 years, or in the city of Inuyama, Aichi. In Guilin, China, cormorant birds are famous for fishing on the shallow Lijiang River.

In Gifu, the Japanese Cormorant (P. capillatus) is used; Chinese fishermen often employ Great Cormorants (P. carbo).

Activity Procedure 1. In your groups, predict whether a cormorant must aim above, below, or directly at a fish in order to pierce it. 2. Assign a viewer (make observations), recorder (record observations), reporter (report observations to the class), and reader (read the activity instructions). 3. Place an opaque cup in front of the group’s viewer, the person should be able to see down the cup but at an angle. 4. Place a coin into the opaque cup and place it until it is out of view. 5. Pour water into the cup until it becomes completely visible. 6. Record the height of the water in centimeters. 7. Repeat the procedure for oil and alcohol. Record the height of each on the data table.

Data Sheet

Water Oil Alcohol

Height of Liquid

Refraction of Light

(cm)

(little, moderate, severe)

Light & Optics Unit Becky McCoy Response Questions Answer these questions for homework in the form of a short essay. • Describe what has happened? • What allows you to see the coin? • Why is it that we did not see the coin until the water, oil, or alcohol were added? • Based on the experiment, where would a cormorant aim? • Does this prove or disprove your hypothesis? • Restate your hypothesis if necessary.