Refraction
What’s this called again? Explain what we are seeing.
(c) McGraw Hill Ryerson 2007 Light Can Be Refracted When light travels from one transparent medium to another of a different density, it changes speed, and refracts The bending of light, due to a change in speed, is called refraction. See page 174 (c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007 Light Can Be Refracted Eg. Light rays entering this glass block will bend (refract) because the glass is more dense, causing the rays to slow down. Once inside the glass the light rays move in a straight line. What will happen when the light rays leave the glass and move back into air, which is less dense? See page 174 (c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007 Light Can Be Refracted They will travel faster and change direction again (refract) See page 174 (c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007 Angle of Refraction The angle of refraction is measured from the refracted ray to the normal. See page 174 (c) McGraw Hill Ryerson 2007
Refraction of Light in Water Objects in water appear in a different location than they actually are. This is due to the refraction of the light. See page 175 Take the Section 5.1 Quiz (c) McGraw Hill Ryerson 2007
How do we know which way the light will bend?
(c) McGraw Hill Ryerson 2007 When light moves from a LESS dense medium to MORE dense, the light rays bend TOWARD the normal: (c) McGraw Hill Ryerson 2007
(c) McGraw Hill Ryerson 2007 When light moves from MORE dense LESS dense, rays bend AWAY from the normal: (c) McGraw Hill Ryerson 2007
Is it the same for different gases?
Is it the same for different gases? Yes
(c) McGraw Hill Ryerson 2007 What’s happening here? See page 175 Take the Section 5.1 Quiz (c) McGraw Hill Ryerson 2007
Refraction of Light in Air Warm air is less dense than cold air. Mirage: An illusion (misleading appearance), like the appearance of water on the road ahead on a hot day. Reason: Air closer to the ground is warmer and therefore less dense. Light from the sky is refracted upward as it enters the less dense air. The “pools of water” are actually images of the sky refracted by warm air near the ground. See page 175 Take the Section 5.1 Quiz (c) McGraw Hill Ryerson 2007
Refraction of Light in Air The “pools of water” you see on the highway on a hot day is due to the air closer to the ground is hotter and less dense than air higher up. Light from the sky directed at the ground is bent upward as it enters the less dense air. The “pools of water” are actually images of the sky refracted by warm air near the ground. See page 175 Take the Section 5.1 Quiz (c) McGraw Hill Ryerson 2007
Homework: Practice WS: BLM 2-17, Go over in class Remaining time: Read pages 172-175, Answer Reading Check Questions #6, 7 page 175 Answer Check your Understanding p181 #6,7, 11