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Q102
(CDS-II/2020)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Geometrical optics
Answer Verified
A luminous object is placed at a distance of 40 cm from a converging lens of a focal length of 25 cm. The image obtained in the screen is ________.
Result
Your answer:
—
·
Correct:
C
Explanation
For a converging lens, the focal length (f) is +25 cm and the object distance (u) is -40 cm [1]. Using the lens formula 1/f = 1/v - 1/u, we find 1/v = 1/25 + 1/(-40), which simplifies to 1/v = (8 - 5)/200 = 3/200. Thus, the image distance (v) is +66.67 cm. Since v is positive, the image is real and formed on the opposite side of the lens, which means it can be caught on a screen and is naturally inverted. The magnification (m = v/u) is 66.67 / -40 = -1.67. A magnification magnitude greater than 1 indicates the image is enlarged (magnified), and the negative sign confirms it is inverted. Therefore, the image is inverted and magnified.
Sources
- [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > 9.3.7 Lens Formula and Magnification > p. 155
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