Mirrors and Reflection

Law of Reflection

•Angle of incidence equals the angle of reflection

• Whatever angle the light hits the surface, it will bounce back at the same angle

However…..….the shape of the reflecting surface affects the way light reflects from it

Plane Mirror• Has a flat surface• Reflection is upright and same

size• Images are reversed• Examples: bathroom mirror,

rearview mirror in a car

Concave Mirror• Curved inward• If the object is close to the mirror, the

image is enlarged and upright• If the object is far away, the image is

reduced in size and upside down• Examples: inside of a spoon, reflecting

telescope, inside of a flashlight

Convex Mirror• Curves outward• The image is upright and smaller• Useful because they allow you to

see a large area• Examples: side mirrors on cars,

back of a spoon, used for security

Lenses and Refraction

•The shape of the lens affects how the light will refract.

Convex Lens• Thicker in the middle than at the

edges• Light refracts towards the center

(converges)• Examples: magnifying glasses,

human eye, cameras, projectors

http://www.google.com/url?sa=i&rct=j&q=convex+lens+ray+diagram&source=images&cd=&cad=rja&docid=sLGJCZnwAVGgGM&tbnid=-BSPdn1U2FzTaM:&ved=0CAUQjRw&url=http://mrclarkrbhs.wikispaces.com/Flashlights,+Searchlights+and+Car+Headlights&ei=IFwQUcHCNIGc9QSzpYHwDA&bvm=bv.41867550,d.eWU&psig=AFQjCNHyMzXfuehl_wVNVYUHREsZn1hMDg&ust=1360112982112288

Concave Lens• Thinner in the middle than

at the edges• Light spreads out (diverges)• Examples: used in

telescopes

http://www.google.com/url?sa=i&rct=j&q=concave+lens+ray+diagram&source=images&cd=&cad=rja&docid=RaYP9IXmOET28M&tbnid=cpSqMkxzm8IOFM:&ved=0CAUQjRw&url=http://www.physicsatstrathaven.co.uk/sgrade/health%20physics/health_revision.html&ei=tlwQUfW3KYzg8ASc94DoBg&bvm=bv.41867550,d.eWU&psig=AFQjCNFmK3hxeRRNLuG_gMwfN-LgGYNLbQ&ust=1360113161523556

How are lenses used to correct human

vision?

Nearsightedness (Myopia)• Can only see an object clearly if

its nearby• Eye is too long and the lens

focuses light in front of the retina• Concave lens is used to correct

this

http://www.google.com/url?sa=i&rct=j&q=nearsightedness&source=images&cd=&cad=rja&docid=LebMKDPrOjXpEM&tbnid=OW3iMzE9BRjueM:&ved=0CAUQjRw&url=http://biology-forums.com/index.php?action=gallery;sa=view;id=8202&ei=3l0QUYaOF4PM9QTi6ICoDg&bvm=bv.41867550,d.eWU&psig=AFQjCNFk3gXHOARup3hrNds0pPVVhCLk-A&ust=1360113458510182

Farsightedness (Hyperopia)• Can only see an object clearly

if its far away• Eye is too short and lens

focuses behind the retina• A convex lens is used to

correct this

http://www.google.com/url?sa=i&rct=j&q=farsightedness&source=images&cd=&cad=rja&docid=ePOLlGJYmw4LMM&tbnid=bag6W8X8a634oM:&ved=0CAUQjRw&url=http://biology-forums.com/index.php?action=gallery;sa=view;id=8201&ei=Sl4QUbi8BIra8AToq4CgBw&bvm=bv.41867550,d.eWU&psig=AFQjCNGmEqiE4VyPrKb7jFJ0WPLWvTRgwQ&ust=1360113569574066