Name the part of our eyes that helps us to focus near and distant objects in quick succession.
Name the part of our eyes that helps us to focus near and distant objects in quick succession.
The part of our eyes that helps us to focus on near and distant objects in quick succession is the ciliary muscles (by modifying the curvature and focal length of the crystalline eye lens).
Marking Scheme
- 1Identification of ciliary muscles (or ciliary muscles modifying the eye lens) (1 mark)
Hint
Think of the muscular structure that contracts and relaxes to change the thickness (and thus the focal length) of the eye lens.
Quick Oral Answer
The ciliary muscles alter the focal length of the eye lens by changing its curvature, allowing us to focus on objects at different distances.
Analysis & Explanation
According to the NCERT text, the curvature of the eye lens can be modified to some extent by the ciliary muscles.
- When the ciliary muscles relax, the lens becomes thin, its focal length increases, enabling us to see distant objects clearly.
- When the ciliary muscles contract, the curvature of the eye lens increases, the lens becomes thicker, and its focal length decreases, enabling us to see nearby objects clearly.
This rapid adjustment of focal length is known as the power of accommodation.
Common Mistakes
- 1Students often write 'iris' or 'pupil', which control the amount of light entering the eye, rather than the ciliary muscles which control focus.
- 2Writing only 'eye lens' without mentioning the 'ciliary muscles' which actually perform the action of changing its shape.
Interesting Facts
The human eye can change its focus from a distant horizon to a book in your hand in about 350 milliseconds!
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2010?
This question carries 1 mark in the CBSE Class 10 Science 2010 examination.
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.
What topic does this question cover in Science?
This question covers the topic "Power of Accommodation" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2010 paper?
This is a Very Short Answer question from Section A in the CBSE Class 10 Science 2010 paper.