5Reflection of LightReflection occurs when a wave bounces back after striking a barrier.Example: a reflection in a mirror.
6Three things that affect how light is reflected: Surface of the ObjectColor of the ObjectShape of the Object
7Clear vs. Diffuse Reflection Surface of the ObjectClear vs. Diffuse ReflectionSmooth, shiny surfaces have a clear reflection:Rough, dull surfaces have a diffuse reflection.Diffuse reflection is when light is scattered in different directions
10Color of the ObjectEver notice that an asphalt driveway seems hotter on a summer day than a concrete sidewalk?This occurs because light that is not reflected from the surface of an object may be absorbed by the object and converted into thermal energy.
11Shape of the Object Reflection from a mirror: Mirror Normal Incident rayReflected rayAngle of incidenceAngle of reflectionMirror
12Angle of incidence = Angle of reflection The Law of ReflectionAngle of incidence = Angle of reflectionIn other words, light gets reflected from a surface at ____ _____ angle it hits it.The same !!!
15Plane Mirrors Flat Surface Light is reflected straight back, resulting in an upright image that is the same size as the original object.
16Concave Mirrors Curves Inward (like 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.If the object is very far away, the image is reduced in size and upside down.
17Convex Mirrors Curves Outward Results in an image your eyes detect as upright and reduced in size.The side mirrors on cars are convex mirrors. (Objects in mirror are closer than they appear.)
19Refraction of LightRefraction is the bending of a wave as it passes from one medium to another.
20What causes the light to bend? What’s different about air and water?DENSITY – the amount of mass in a certain volume of a substance (mass/volume)AIRWATERgasliquid
21Example of RefractionWhen a straw is placed in water it looks like this:In this case the light rays are slowed down by the water and are bent, causing the straw to look broken. The two mediums in this example are air and water.
22Another Example:When you use a magnifying glass, the object appears larger because of refraction.The light waves traveling in the air change direction when they enter the glass of the lens, and then again when they move from the glass back into the air again.Lens
23Diffraction of LightDiffraction is the bending, spreading, and interference of waves when they go through a narrow opening.
24Diffraction PatternsRadio waves can diffract around hills, mountains or even the whole planet.Light waves can diffract through tiny slits.X-rays can diffract around atoms.
25Electromagnetic waves have a huge range of wavelengths. If the wavelength is of a similar size to a gap in a harbor wall, then the wave will diffract as shown below.
26If the wavelength does not match the size of the gap, then only a little diffraction will occur at the edge of the wave.
27Transmission of LightTransmission is the passing of waves through a medium.
28Think about a radio station… An electromagnetic wave is produced.The wave travels from the stations transmitter out in all directions at the speed of light.Even though you cannot hear radio waves when your radio’s turned off, the waves are still being transmitted in the room.
29What happens when light hits these objects? Glass of waterSchool bus windowNotebook paperWaxed paperPlastic wrapTissue paperCardboardTextbookHand lens…
30Many materials are classified by how well they transmit light. Three Types of Materials:TransparentTranslucentOpaque
31TransparentA material that permits light to pass through
32Transparent objects: ALL of these are transparent. The windows on a school bus,A clear empty glass,A clear window pane,The lenses of some eyeglasses,Clear plastic wrap,The glass on a clock,A hand lens,Colored glass…ALL of these are transparent.Yes, we can see through them because light passes through each of them.
33TranslucentA material that transmits some light but also scatter light in all directions
34Translucent objects:Thin tissue paper,Waxed paper,Tinted car windows,Frosted glass,Clouds,All of these materials are translucent and allow some light to pass but the light cannot be clearly seen through.
35OpaqueA material that allows no light to pass through
36Opaque objects:Heavy weight paper,CardboardAluminum foil,Mirror, bricks, buildings,Your eyelids and hands,Solid wood door,All of these objects are opaque because light cannot pass through them at all.They cast a dark shadow.
37ShadowsShadows are places where light is “blocked”:Rays of light