The erect image formed by a concave mirror is of size double the size of object. How are u and v related?
Magnification (m) = - image distance (v)object distance (u)\dfrac{\text {image distance (v)}}{\text{object distance (u)}}object distance (u)image distance (v)
Given,
2 = - vu\dfrac{\text v}{\text u}uv
Hence, v = -2u
