Question

Now, I'll give all of you an activity to do when the sun comes up in your respective countries.
Go outside with a pencil and bring it close to the ground, pointing it horizontally.
You'll see its sharp shadow on the ground.
Now start raising the pencil, still pointing horizontally. The rays of the sun start invading the region of geometric shadow until, after some height, the shadow is almost non-existent.
This happens with the leaves of a tree, a building and what not.
My question is, WHY???

Answer 1

there is a simple thinhg u need to know that light travels in all directions
when a shadow is formed? when an object blocks the passage of light through it so when the pencil is close at ground u are restricting other sources of light(in the horizontal direction===in the plane of the shadow)

as u raise it up the light from other points come at the shadow point and the pencil's image might also become big depending on where the sourse of light is falling on the pencil(the shadow is called the projection of the object on the surface where it falls(property under resolving vectors)

Answer 2

on a dully illuminated room u can see darker shadows
in a bright room the darkness is not much.....observe seeing is believing!