Q27
1 markMCQSection B

Study the given ray diagrams and select the correct statement from the following:

Figure for question 27
Also asked in:2017
Light — Reflection and Refraction
Mirrors and Lenses

Options

(A)Device X is a concave mirror and device Y is a convex lens, whose focal lengths are 20 cm and 25 cm respectively.
(B)Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 10 cm and 25 cm respectively.
(C)Device X is a concave lens and device Y is a convex mirror, whose focal lengths are 20 cm and 25 cm respectively.
(D)Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 20 cm and 25 cm respectively.
Official Answer

Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 20 cm and 25 cm respectively.

convex lensconcave mirrorfocal length

Marking Scheme

  • 1Identify the type of optical device (mirror or lens)
  • 2Determine the focal length of each device

Hint

To solve this question, the student needs to understand the properties of convex lenses and concave mirrors, and how they affect the path of light rays. They should also be able to read and interpret ray diagrams.

Quick Oral Answer

Device X is a convex lens because the rays are converging after passing through it, and its focal length is 20 cm. Device Y is a concave mirror because the rays are converging after reflecting from it, and its focal length is 25 cm.

Analysis & Explanation

The question requires the student to analyze the ray diagrams and identify the type of optical device (mirror or lens) and its focal length. The correct answer is option D, which states that device X is a convex lens and device Y is a concave mirror, with focal lengths of 20 cm and 25 cm respectively.

Common Mistakes

  1. 1Confusing the type of optical device
  2. 2Incorrectly reading the focal length from the ray diagram

Interesting Facts

Convex lenses are used in magnifying glasses and binoculars

Concave mirrors are used in telescopes and solar concentrators

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2017?

This question carries 1 mark in the CBSE Class 10 Science 2017 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Light — Reflection and Refraction" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Mirrors and Lenses" from CBSE Class 10 Science.

Has this question appeared in other CBSE Science papers?

Yes, a similar question appeared in the 2017 CBSE Class 10 Science paper.

What type of question is this in the CBSE Class 10 Science 2017 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2017 paper.