Question

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 the eye in line with $PA$. When the student shifts the 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. $x>2f$

Answer 1

The correct option is B $f<x<2f$

Since the object and the image move in opposite directions, the position of the object should be in between $f$ and $2f$.
So, $f<x<2f$