In an experiment to determine the focal length (f) of a concave mirror by the u-v method, a student places an object pin A on the principal axis at a distance x from the pole P. The student looks at the pin and its inverted image from a distance keeping his/her eye in line with PA. When the student shifts his/her eye towards left, the image appears to the right of the object pin.Then,
(a)x < f
(b)f < x < 2f
(c)x = 2f
(d)x > 2f ?
1Ans is (b).!!
Reason (This might not be an authenticated one, just an experimental view !!) : when the object is in b/w centre and focus, image will form away from centre. When we keep our eye along the line PA, we cannot see the image as it is behind us. When we slightly move it to the left, the image appears to be moving right (try imagining :P)
correct me if i am wrong !
11http://targetiit.com/iit_jee_forum/posts/optics_electricity_4025.html
same question asked here and explained too
