Guess Paper 2014Q. (a) List the factors on which scattering of light depends. (b) What is Tyndals, effect ?
Q. A student sitting on the last bench in a class room cannot read the black board clearly.
(i) Name the kind of defect of vision the student is suffering from.
(ii) Name the type of spherical lens he has to use to correct this defect.
(iii) State two possible reasons for this defect of vision.
Q. Why do stars appear to twinkle while the planets do not ? Explain with the help of diagram.
Q. Explain with the help of diagram why the sun is visible to us two minutes before the actual sun-rise and two minutes after the sunset.
Q. (a) What is meant by power of accommodation of eye ? A person with a defective vision cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision ? Draw a diagram of thus corrected eye. (b) A person having presbyopia uses a bifocal lens to restore proper vision. Which part of the this lens is convex and which part is concave ?
Q. Name the part responsible for the power of accommodation of the human eye.
Q. What is meant by least distance of distinct vision ? How does this vary between the very young and old people ?
Q. Explain why the colour of the clear sky is blue.
Q. State the cause of dispersion, when white light enters a glass prism. Explain with a diagram
Q. What is a rainbow ? When and how is it formed ?
Q. Explain the cause of the red colour of the Sun at Sunrise and Sunset.
Q. List two causes leading to myopia of the eye. Draw ray diagrams to show the image formation in case of defective eye and corrected eye.
Q. We can see the sun for few minutes even after it has actually set. Why ?
Q. A student has difficulty in reading the blackboard while sitting in the last row. What could be the defect of vision the student is suffering from ? What are the causes for this disorder ?
Q. What is meant by power of accommodation of eye ? The minimum power of eye lens is 40D. If the far point of normal eye is infinity find the size of eye ball.
Q. The sky appears dark to the passengers flying at very high attitudes. Why ?
Q. A child has difficulty in reading the blackboard while sitting on the last bench in a class room. What could be the defect the child is suffering from ? List two main causes of this defect.
Q. State the nature of the image formed at the retina of human eye.
Q. (a) What is the near point of the human eye with normal vision ? (b) Why is a normal eye not able to see clearly the objects placed closer than the near point ?
Q. The sun appears oval (or flattened) at sunrise and sunset, but appears circular at noon. Explain, why ?
Q. A student has difficulty in reading the black board while sitting in the last row
What could be the defect the student is suffering from ? How can it be corrected ? Draw the ray diagrams for (a) defective eye (b) its correction.
Q. State the range of the human eye with a normal vision
Q. Q. �Stars seem higher than they actually are� Explain, why?
Q. What is meant by the power of accommodation of the eye? State the role of ciliary muscles in achieving it.
Q. (a) What is long sightedness? List its causes. (b) How can it be corrected? Draw the ray diagram for its correction.
Q. Define absolute refractive index of a medium. Light enters from air to water having refractive index 4/3. Find the speed of light in water. The speed of light in vacuum is 3x108 m/s.
Q. With the help of a diagram, explain the formation of a rainbow in the sky.
Q. (i) What is meant by �least distance of distinct vision� ? (ii) How does iris controls the size of the pupil in bright light and dim light ?
Q. A person can see distant sign boards clearly but cannot read clearly a book which is at 25 cm from his eye. Identify the defect. Draw a labelled ray diagram to illustrate how this defect can be corrected.
Q. A person needs a lens of power � 2.5 dioptres for correcting his vision. Name the defect of vision he is suffering from. Which lens will he be using for the correction ? Also find the focal length of the lens.
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