Just plz ! why does the lightbulb in the right electrical circuit turn on but not the one on the left?

In the open circuit the current cannot flow from one end of the power source to the other. Because of this there is no current flow, and therefore the light does not turn on.

*This is not my answer*

explanation:

v=uf/(u-f)

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

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.