$(a)$ Write the relation between $u, v, f$ for lenses and for mirrors,where $u, v, f$ are object distance,image distance,and focal length respectively.
$(b)$ The magnification produced by a concave mirror is $m = +4$. Write the information about the image given by this statement.
$(c)$ Draw a ray diagram for the following and show the formation of the images in the case of a concave mirror when the object is placed:
$(i)$ Between the pole and the focus point.
$(ii)$ At the centre of curvature.

(N/A) $(a) (i)$ For lenses,the lens formula is $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$.
$(ii)$ For mirrors,the mirror formula is $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$.
$(b)$ Since the magnification $m = +4$ is positive,the image is virtual and erect. Since the magnitude of $m$ is $4$ (which is greater than $1$),the image is magnified (enlarged).
$(c)$ $(i)$ When the object is placed between the pole $(P)$ and the focus $(F)$ of a concave mirror,a virtual,erect,and magnified image is formed behind the mirror.
$(ii)$ When the object is placed at the centre of curvature $(C)$ of a concave mirror,a real,inverted image of the same size as the object is formed at the centre of curvature $(C)$.