Sunday, October 21, 2012

Human Eyes and Colorful world Science X (10th)

Class X  NCERT Solution, MCQ's  Study Notes, Q & A
Chapter 11 – Human Eyes and Colorful world Science

1. What is the role of pupil in a human eye? [CBSE Exam Paper  2011]
Ans: The pupil controls the amount of light entering the eye.
2. What is the range of vision of a normal human eye? [CBSE Exam Paper  2011]
Ans: 25 cm to infinity
3. Name the part of the human eye that helps in changing the focal length of the eye lens.
[CBSE Exam Paper  2011]
Ans: Ciliary muscles
4. Which coloured component bends the least during the dispersion of white light through prism? [CBSE Exam Paper  2011]
Ans: Red colour deviates the least and violet colour the most.
5. Name the part of the eye [CBSE Exam Paper  2011]
(a) that controls the amount of light entering into the eye. 
(b) that has real, inverted image of the object formed on it.
Ans: The pupil  , Retina
6. A person is advised to wear spectacles with convex lenses. State the defect of vision he is
suffering from. [CBSE Exam Paper  2011]
Ans: Hypermetropia
7. Why is red colour selected for danger signal lights?  [CBSE Exam Paper  2011] 
Ans: Red colour deviates 
8. When one enters a dim-lit room from bright light, one is unable to see the objects in the
room for sometime. Why?  [CBSE Exam Paper  2011]
Ans : Ciliary muscles takes time relax and get original position
9. In an experiment with a rectangular glass slab, a student observed that a ray of light incident at an   angle of 55o  with the normal on one face of the slab, after refraction strikes the opposite face of the slab   before emerging out into air making an angle of 40o  with the normal.  What value would you assign to the angle of refraction and angle of emergence? [CBSE Exam Paper  2011]
Ans: Angle of incidence = 55   
Angle of refraction = cannot be determined       
Angle of emergence = 40  
But if we ignore the language used by CBSE and interpret in usual way
Angle of incidence = 55           Angle of refraction = 40
 Angle of emergence = 55
10. A person is advised to wear spectacles with concave lenses. What type of defect of vision is he suffering from? [CBSE Exam Paper  2011]
Ans: Myopia
11. What will be the observed colour of the sky on a planet where there is no atmosphere? Why?
Ans:  Dark, because no light would be scattered to the observer’s eye

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