Which is a convex lens? (the blue arrows represent the direction of light as it interacts with the lenses.)

Image (c) is a convex lens

Explanation:

The lenses are of two types i.e. concave lens and convex lens. Figure (3) shows a convex lens. The blue arrows represent the direction of light as it interacts with the lenses. It is also known as converging lens. It is because, it converge all the rays of light that are coming parallel to principal axis at focal point (F).

The image formed by convex lens is real and inverted always. But when the object is placed between the focus and the optical center of the lens, the formed image is virtual and erect.

So, the correct option is (c).

multiple

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach