Lentes

http://www.google.com.br/imgres?imgurl=http://www2.fc.unesp.br/experimentosdefisica/opt05_1.gif&imgrefurl=http://www2.fc.unesp.br/experimentosdefisica/opt05.htm&h=332&w=467&sz=5&tbnid=XvcWwUYuVElbUM:&tbnh=91&tbnw=128&prev=/images%3Fq%3Dtipos%2Bde%2Blentes&zoom=1&q=tipos+de+lentes&hl=pt-BR&usg=__JmziB1QSzKlFNFUs9HBPO_fOBEQ=&sa=X&ei=4O2-TL7TFoK78gaRjpG8Bg&ved=0CCYQ9QEwAw