Answer to Question #61979 in Optics for musbahuuuu

Question

13 In practical experiment inloving the use of optical pins, parallax is reduced or removed if on slightly displacing one's eye from side to side
the object and image are not coincident but move together in same directions
the object and image move in opposite directions relative to each other
the object and image are coincident and move together in the same direction
the object and image are coincident and remain stationary
14 In an experiment with a concave mirror, the image of an optical pin which is 4 times its size was cast on on a screen 6m from the object pin. How far from the object pin should the mirror be placed?
8m
6m
3m
2m
15 The image of an object which is between the concave mirror's reflecting surface and its principal focus is
in front of the mirror erect real and diminished
behind the mirror inverted real and diminished
in front of the mirror erect virtual and enlarged
behind the mirror erect virtual and enlarged