Question

If you are casting a shadow of a ball on the wall, how do you make the umbra larger than the ball or is it impossible. Also, how can you make the umbra smaller than the ball or is it impossible? How can you make the radius of the penumbra larger than the balls radius? How can you make the radius of the penumbra smaller than the ball radius?

I know the umbra is the really dark portion where all of light is blocked, but I don't know how to adjust it

Answer 1

put the ball next to the light, the umbrella gets large.

smaller? move the ball close to the sceen.

radius large? see the first answer above.
smaller? move the ball toward the screen, or make the light larger diameter.

Answer 2

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTUujzi6CXKwSzRPDb2VvkGj7Tzly32RzQcIlGFWAOAyBjMxYjqXw

on the radius larger, look at that figure....can the umbra ever be bigger than the radius of the object?

Answer 3

Thank you!

Answer 4

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSQy7OK33WvT0CrizFuRWBeatqSGvdgsmkksVHOlrIpDRiXNUMmFQ