If you hold a magnifying glass so that sunlight passes through it, a bright point of light will be formed in front of the lens. This point is very hot - in fact, magnifying glasses are included in survival kits to start fires.
a) What shape of lens is used to make a magnifying glass - is it thicker at the edges than in the middle, or vice-versa?
b) What is the proper name for the point where the light makes a bright spot?
c) Why is the bright spot so hot? Explain
A "bandshell" is a curved wall built outside where performances can be held - for instance, this bandshell in Central Park, NY:http://centralpark.org/index.php/attractions/bandshell/
What type of optical device does the bandshell act like? Music played in front of the bandshell is clear and audible for a surprising distance in front of the bandshell. Why is this the case? Explain