Question

Sign of magnification of concave lens is

Answer 1

The sign is 1/f = 1/u+ 1/v

Answer 2

Magnification will always be positive for concave lens!

Here is all the details below ↓↓↓  

                      Note :

• f = focal length

• v = distance of image .

• u = distance of object .

Magnification formula :

M = v / u

Concave lens :

f = negative

u = negative

v =  negative

Convex lens

f = positive

u = negative

v = positive for real image ,

v = negative for virtual image .

The optical centre is chosen as the origin of the coordinate system.

With respect to optical centre :

The part which are above are positive, below negative.

The part which are right are positive while left is negative.

This is just like the normal x-axis and y-axis in the co-ordinate system .

Hence magnification will always be -v / - u = v / u ( positive )