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An object is placed at the centre of curvature of a concave mirror of focal length 16 cm. If the object is shifted by 8 cm towards the focus, . the nature of the image would be
Explanation
The focal length (f) of the concave mirror is 16 cm. The radius of curvature (R) is twice the focal length, which is 32 cm [3]. Initially, the object is at the centre of curvature (u = 32 cm). When the object is shifted 8 cm towards the focus, the new object distance (u) becomes 24 cm (32 - 8 = 24 cm). Since the focal length is 16 cm, the object is now positioned between the centre of curvature (32 cm) and the principal focus (16 cm). According to the principles of geometrical optics for concave mirrors, when an object is placed between C and F, the image formed is real, inverted, and magnified [3]. Using the mirror formula 1/f = 1/v + 1/u, the image distance (v) would be -48 cm, confirming it is real (formed in front of the mirror) and larger than the object [3].
Sources
- [3] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > 9.2.4 Mirror Formula and Magnification > p. 143
- [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > What you have learnt > p. 159