The light in this picture is coming from a normal light bulb, in front and above the objects. The shadows are fairly short, and the background isn't lit at all.

This light source is in the same position down about 18 inches. The floor is not as brightly lit, but the background is now visible. The shadows have changed drastically, getting much longer.

The light has moved about 45 degrees clockwise around the objects. It has also moved up about six inches. The shadows got shorter as the light moves up, and they move to the side as the light moves. The right half of the background is now more lit than the left.

The light has stayed at the same height, but moved 135 degrees clockwise. The light is coming from the back, and the background has disappeared into darkness. The glare off the floor is blinding out half the picture, and the front of the opaque objects is now difficult to see.