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Class 10 The Human Eye and the Colourful World worksheet
CBSE Science. Defects of vision and their lenses, dispersion, atmospheric refraction, scattering. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
A short-sighted person cannot see clearly beyond 25 cm. The power of the lens needed to correct this is:
- +4 D
- −4 D
- −8 D
- −0.25 D
Answer
(b) −4 D
a concave lens of focal length −25 cm; P = 100 ÷ (−25)
- 2.
Which part of the eye fine-tunes the focus to form a real, inverted image on the retina?
- The eye lens
- The rod cells
- The cone cells
- The retina
Answer
(a) The eye lens
- 3.
Objects seen through the hot air above a fire appearing to waver is due to:
- scattering of light
- reflection of light
- dispersion of light
- atmospheric refraction
Answer
(d) atmospheric refraction
Hot air is less dense than the cooler air around it, and its density keeps changing.
Section B · short answer
- 4.
Rahul can see clearly only up to 20 cm. Name the defect, and find the nature, focal length and power of the lens needed.
Answer
myopia; concave lens, f = −20 cm, P = −5 D
the lens must make distant objects seem to be at 20 cm: f = −20 cm
- 5.
Arjun is long-sighted, with a near point of 2 m. Find the power and focal length of the lens that lets Arjun read at 25 cm.
Answer
P = +3.5 D (convex); f = 28.57 cm
1/f = 1/25 − 1/200 (in cm), so P = 100/f = 3.5 D
Section C · long answer
- 6.
Zoya sits at the back of the class and cannot read the board, which is farther than 5 m, but can read a book easily. (a) Name the defect. (b) Give two possible causes. (c) Find the type, focal length and power of the lens needed.
Answer
(a) myopia; (b) the eyeball is too long, or the eye lens is too curved; (c) concave, f = −500 cm, P = −0.2 D
the image of a distant object forms in front of the retina; the lens must give a virtual image at 500 cm
Fresh sheets for your child
In the app, every The Human Eye and the Colourful World sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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