If the radius of a raindrop become half, then what happens to its terminal speed?

A capillary tube when dipped into water, it is commonly observed that water will rise through the tube. If the radius of the tube becomes double, what happens to the height of the water column in the tube?

A convex lens of focal length .f is placed in a medium of refractive index equal to that of lens What happens to its focal length?

What is the radius of gyration of the ring about an axis passing through its centre mass and perpendicular to its plane?