In an experiment to determine the focal length `(f)` of a concave mirror by the `u-v` method, a student places the 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,

Options

A. `x lt f`
B. `f lt x lt 2f`
C. `x = 2f`
D. `x gt 2f`

Answer

B

Explanation

Since object and image move in opposite direction the positioning should be as shown in the figure. Object lies between focus and centre of curvature `f lt x lt 2f`