The weight of any object due to the downward force of what?

The "weight" of any object IS the force of gravity between the object and the Earth.

The force is always directed "down", because it's always directed toward the center of the Earth, and we call that direction "down" even though it's a different direction in every place.  

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

a electromagnetic waves