As opposed to concave lenses, which characteristic of convex lenses makes them useful in microscopes

Convex lens, also called a converging lens, because it makes parallel light rays passing through it bend inward and converge at a spot just beyond the lens known as the focal point.

Shy diving is the only sport which doesnot require a high level of physical fitness

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other