(a) (i) An object of $5\mathrm{cm}$ height is placed at a distance of $20\mathrm{cm}$ from the optical centre of a concave lens of focal length $18\mathrm{cm}$ . Calculate (1) image distance and (2) the magnification in this case. (ii) Compare the values of magnification obtained by a concave lens and a convex lens when both the lenses form virtual images. OR (b) A convex lens can form a (i) real, inverted and magnified image as well as (ii) virtual, erect and magnified image of an object. If the focal length of the lens is $10\mathrm{cm}$ , what should be the range of the object distance in both cases? Draw ray diagrams to justify your answer.

Q: (a) (i) An object of $5\mathrm{cm}$ height is placed at a distance of $20\mathrm{cm}$ from the optical centre of a concave lens of focal length $18\mathrm{cm}$. Calculate (1) image distance and (2) the magnification in this case. (ii) Compare the values of magnification obtained by a concave lens and a convex lens when both the lenses form virtual images. OR (b) A convex lens can form a (i) real, inverted and magnified image as well as (ii) virtual, erect and magnified image of an object. If the focal length of the lens is $10\mathrm{cm}$, what should be the range of the object distance in both cases? Draw ray diagrams to justify your answer.

The lens maker’s formula is $\frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$ where $f$ is the focal length of the lens, $\mu$ is the refractive index of the material of the lens and $R_1$ and $R_2$ are the radii of curvature of the two surfaces of the lens. The power of a lens is the reciprocal of its focal length, i.e., $P = \frac{1}{f}$ . The focal length of a lens of power $-2.5 \mathrm{D}$ is $f = \frac{1}{P} = \frac{1}{-2.5} = -0.4 \mathrm{m} = -40 \mathrm{cm}$

Q: How many marks does this question carry in CBSE Class 10 Science 2023?

This question carries 3 marks in the CBSE Class 10 Science 2023 examination.

Q: Which chapter does this question come from in Science?

This question is from the chapter "The Human Eye and the Colourful World" in the CBSE Class 10 Science syllabus.

Q: What topic does this question cover in Science?

This question covers the topic "Refraction of Light" from CBSE Class 10 Science.

Q: What type of question is this in the CBSE Class 10 Science 2023 paper?

This is a Short Answer question from Section C in the CBSE Class 10 Science 2023 paper.

Question

(a) (i) An object of $5\mathrm{cm}$ height is placed at a distance of $20\mathrm{cm}$ from the optical centre of a concave lens of focal length $18\mathrm{cm}$ . Calculate (1) image distance and (2) the magnification in this case. (ii) Compare the values of magnification obtained by a concave lens and a convex lens when both the lenses form virtual images. OR (b) A convex lens can form a (i) real, inverted and magnified image as well as (ii) virtual, erect and magnified image of an object. If the focal length of the lens is $10\mathrm{cm}$ , what should be the range of the object distance in both cases? Draw ray diagrams to justify your answer.

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