Question

Please tell how to solve 45th numerical

Answer 1

let size of the object is ho
and that of image is hi=3ho
now..
magnification =m= hi/ho=3ho/ho=3
now m = 3 = -v/u
v=-3u
now by mirror formula
1/f=(1/v)+(1/u)
1/-18=(1/-3u)+1/u
-1/18=2/3u
3u/2=-18
3u=-36
u=-12
therefore position of the object is -12cm

Hope this helps:p