An object is placed 18cm iin fromt of speherical mirror. If the image is formed at 4cm to the right of the mirror , calculate the focal length of the mirror.Is the mirror concave or convex , what is the nature of the image and its radius of curvature.

since the image is formed to the right of the mirror, i.e. it is formed at the backside of the mirror.

Hence it is virtual.

object position, u = -18

image position, v = +4

let focal length be, f

using the mirror equation:

1/v + 1/u = 1/f

thus we can get the value for f

if it is positive, the mirror is convex else it is convex