In parallax method for the determination of focal length of a concave mirror, the object should always be placed: (a) between the focus (F) and the centre of curvature (C) of the mirror ONLY (b) between the pole (P) and the focus (F) of the concave mirror ONLY (c) at any point beyond the focus (F) of the mirror (d) beyond the centre of the curvature (C) of the mirror ONLY

Answer: (c). The parallax method locates a real, inverted image with a pin, so the image must be real. A concave mirror forms a real image for every object position beyond the focus F. So the answer is (c) at any point beyond F.

In parallax method for the determination of focal length of a concave… | JEE Main 2026 (22 Jan, Shift 2)

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Reflection & Mirrors

In parallax method for the determination of focal length of a concave mirror, the object should always be placed:

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Answer: (c)

The parallax method locates a real, inverted image with a pin, so the image must be real.
A concave mirror forms a real image for every object position beyond the focus $F$ .
So the answer is (c) at any point beyond $F$ .

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