Homework: Page 525, #2-9

Phenomena Related to Refraction Apparent Depth: A pencil partly under water looks bent when viewed from above Our brain perceives that light rays always travel in a straight line Light from the pencil tip reaches our eyes and our brain then projects the rays in a straight line to create a virtual image in the water The virtual image is higher than the actual pencil tip….so it appears bent

Fish in water appear nearer the surface than they actually are…

Internal Refraction When a light ray travels from water into air at an angle, it bends (refracts) away from the normal. The angle of refraction is greater than the angle of incidence

Critical Angle What would happen if the angle of incidence kept getting larger? Eventually the angle of refraction would reach 90 degrees Critical Angle: The angle of incidence that produces an angle of refraction of 90 degrees

Total Internal Reflection When the angle of incidence is greater than the critical angle (The angle of incidence that produces an angle of refraction of 90 degrees), the light ray is no longer refracted Instead, it is reflected back into the water This is called total internal reflection and occurs when light is reflected (internally) back into the water (or other medium) This happens when the incidence angle is greater than the critical angle Eg. Diamonds copy

Diamonds Great example of total internal reflection When light rays enter a diamond, they experience several total internal reflections before traveling back into the air (due to the cut of the diamond) These total internal reflections cause the diamond to sparkle

Activity: Measuring the Critical Angle for Various Media Pg. 532 Analyze & Reflect - abc Apply & Extend - d

Textbook Read pages Answer #1-9