Question

the image of an object placed on the principal axis of a concave mirror of focal length 12 cm is formed at a point which is 10 cm more distant from the mirror than the object. find the magnification of the image .

Answer 1

Let object distance be 'x'cm according to question 1/f=1/v+1/u 1/-12=1/x+ 1/x+10 by solving this we get x =20 or -6 m= -v/u = -x+10/x= -(-6+10)/-6=2/3

Answer 2

v=u-10(because in concave mirror image is formed in front of mirror)
1/f=1/u-10+1/u
u=-6,v=-16
m=-8/3