Waves & Medium

1. Waves & Medium • Any substance that a wave moves through is a medium • Sound waves, Earthquake waves, and ocean waves all require matter to transfer energy

2. Waves & Medium • Electromagnetic waves can transmit energy through a vacuum or empty space.

3. How does medium affect wave behavior? • Wave behavior is affected by the type of medium the wave interacts with or travels through.

4. Light Waves and Media • In order for you to see any object, the object must give off light. • Objects give off light in only two ways • Being luminous • Being illuminated

5. Light Waves and Media • Luminous objects are those that emit their own light • Illuminated objects are those that can reflect light to your eyes • The amount of light that is reflected from an object depends on the surface of the object.

6. Light Waves and Media • A smooth surface reflects more light than a rough surface • This occurs because a rough surface scatters reflected light in many different directions

7. Light Waves and Media • Have you ever noticed that an asphalt driveway seems hotter on a summer day than a concrete sidewalk

8. Light Waves and Media • This occurs because light that is not reflected from the surface of an object may be absorbed by the object and converted to thermal energy

9. Light Waves and Media • The color and surface texture of a material have an effect on whether how easily light is absorbed by the object • Smooth and light colored objects reflect more light than they absorb

10. Light Waves and Media • Objects with a rough texture and dark color absorb more light than they reflect • A dark rough textured object will often feel hotter than a smooth, light colored object

11. Shape Affects Deflection • When light rays reflect from a surface they do so in a predictable way that is explained by the Law of Reflection

12. Shape Affects Deflection • The Law of Reflection states that the angle at which any wave strikes a reflecting surface is equal to the angle at which the wave is reflected from the surface

13. Shape Affects Deflection • The angle at which a wave strikes a surface is called the angle of incidence • The angle of at which a wave is reflected from a surface is called the angle of reflection

14. Shape Affects Deflection • According to the Law of Reflection, the angle of incidence is equal to the angle of reflection • The shape of a surface affects how it reflects light.

15. Shape Affects Deflection • A plane mirror is a mirror with a flat surface • Light striking a plane mirror is reflected straight back, resulting in an upright image that is the same size as the original object

16. Shape Affects Deflection • Curved mirrors reflect at an angle, producing different kinds of images

17. Shape Affects Deflection • A convex mirror curves outward, resulting in an image your eyes detect as upright and reduced in size * The side mirrors on cars are convex mirrors

18. Shape Affects Deflection • A concave mirror curves inward, taking the shape of the inside of a bowl • If an object is very close to the mirror, light is reflected in a way that an enlarged, upright image is produced.

19. Shape Affects Deflection • If the object is very far way, the image is reduced in size and upside down

20. Transmission of Light • Many materials are classified according to how well they transmit light • A material that permits light to pass through is transparent

21. Transmission of Light • Whether or not an object is transparent depends on how much and what colors of light it transmits • You can see through the transparent materials • Air and clear glass are examples of common transparent materials

22. Translucent • Translucent materials transmit some light but also scatter light in all directions • Frosted glass and waxed paper are translucent materials

23. Translucent • Opaque materials allow no light to pass through • wood, carpet, and ceramic plates are examples of opaque objects

24. Media and Wave Speed • The speed at which a wave travels is called wave speed • Wave speed is affected by the medium through with a wave travels • Mechanical waves require matter to transmit energy

25. Media and Wave Speed • The more densely packed the matter, the more quickly the energy is transmitted • Sound travels more quickly through solids than through liquids or gases

26. Media and Wave Speed • When waves travel through gases, the temperature of he media affects the wave speed of sound waves. • The higher the temperature of the gas, the faster the particles will move • Light and other types of electromagnetic waves do not require matter to transmit energy

27. Media and Wave Speed • In a vacuum all electromagnetic waves travel at the same speed, 300,000 kilometers per second • When such waves encounter matter, their speed will change, depending upon how they interact with the matter