QUESTIONS: (5 marks each)
Q1. What is atmospheric refraction? Use this phenomenon to explain the following natural events.
- Twinkling of stars
- Advanced sunrise and delayed sunset.
Draw diagrams to illustrate your answers.
Q2. A person needs a lens of power -6D for correcting his distant vision. For correcting his near vision, he needs a lens of power +2D.Find the focal length of the lens and its nature required for correcting distant vision and near vision.
Q3. Which colour of light bends least and which one the most while passing out from the prism? Also state the reason for the same.
Q4. Explain how the components of white light can be recombined after a prism has separated them. Explain with the help of figure.
Q5. On the basis of this activity explain why sky appears red at sunrise or sunset.
Q6. What is a Tyndall effect? How is it caused? What are the conditions required to see a Tyndall effect? Give any two examples of natural phenomenon which show Tyndall effect.
Q7. A 14 year old student is not able to see clearly the questions written on the black board placed at a distance of 5 m from him.
- Name the defect of vision he is suffering from.
- With the help of a labeled ray diagram show how this defect can be corrected.
- Name the type of lens used to correct this defect.
Q8. What is presbyopia? Write two causes of this defect.
Q9. What is myopia? State the two causes of myopia. With the help of labeled ray diagrams show:
- the eye defect myopia.
- Correction of myopia using a lens
- Why is the normal eye unable to focus on an object placed within 10 cm from the eye?
Q10. Why is dispersion of white light? What is the cause of such dispersion? Draw a diagram, to show the dispersion of white light by a glass prism.
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