Question: Shadows from a diagonal sorce of light in a cylinder

[lennon]

I have trouble to put the right light in a cilindrical shape or a box shape when it's place diagonally from the sorce of light.
Obviously it will get reflexions on the bottom, depending on the color of the surface. But I can't get wether if the bottom will get darker or not.
Could someone make a drawing of this for me.
If posible, show some different angles (of the same figure, not of the position of the cylinder).
I feel stupid for not beeing able to figure it out .

[ArtEdGradStudent]

The best thing to do is get a real cylinder and lamp and try it from life. Buy either a Quaker Oats tin, a Folger's Crystals can, or a Pringle's tin, and try moving the lamp around it, seeing how it changes the light on it - in a darkened room. If the images on the cans are distracting, just paint over them some neutral color, like white or gray.

[lennon]

Thanks, I should try that.