To find the focal length of a concave mirror, Sita should choose which one of the following set-ups ?
To find the focal length of a concave mirror, Sita should choose which one of the following set-ups ?
Options
To find the focal length of a concave mirror by focusing a distant object, the complete and correct set-up requires:
- A concave mirror to converge the parallel rays from a distant object.
- A screen to capture the sharp, real, and inverted image of the distant object.
- Holders for both the mirror and the screen to keep them stable and aligned along the same axis.
- A scale to measure the distance between the mirror and the screen, which represents the focal length ().
Therefore, option D is the correct choice.
Marking Scheme
- 11 mark
Hint
Think about what physical objects you need to project an image and how you will measure the distance to find the focal length.
Quick Oral Answer
We need a concave mirror, a screen, holders for both, and a measuring scale. The distance between the mirror and the screen when a sharp image of a distant object is obtained gives the focal length.
Analysis & Explanation
To experimentally determine the focal length of a concave mirror, we use the distant object method. Parallel rays coming from a distant object (like a tree or the Sun) converge at the principal focus of the concave mirror after reflection.
- Why Option D is correct: It lists all the essential apparatus required to perform the experiment successfully: the optical components (mirror and screen), mechanical supports (holders), and the measuring instrument (scale).
- Why Option A is incorrect: It lacks the mirror, the screen, and the measuring scale.
- Why Option B is incorrect: It lacks the mirror, the screen, and the mirror holder.
- Why Option C is incorrect: It lacks the actual mirror and screen, providing only the holders and scale.
Common Mistakes
- 1Choosing options that only list holders and scales without the actual optical elements (mirror and screen).
Interesting Facts
The image formed by a concave mirror of a highly distant object is real, inverted, and highly diminished (point-sized) right at its focus.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2011?
This question carries 1 mark in the CBSE Class 10 Science 2011 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 "Spherical Mirrors" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2011 paper?
This is a MCQ question from Section B in the CBSE Class 10 Science 2011 paper.