Why does lightning travel from clouds to the ground?

Cloud-to-ground lightning comes from the sky down, but the part you see comes from the ground up. A typical cloud-to-ground flash lowers a path of negative electricity (that we cannot see) towards the ground in a series of spurts. Objects on the ground generally have a positive charge.

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length

answer///scientific method;