 okay guys so an object of size 7 cm is placed as 27 cm in front of a concave mirror of focal length 18 so focal length of a con the cave the mirror is negative clear shot shot the object is 7 cm in height and 27 cm is the distance we know that object distance is always taken as negative clear at what distance from the mirror should a screen be placed so that a sharp focused image can be obtained find the size and the nature of the image so