QUESTIONS: (1 Mark each)
Q1. Which phenomenon is responsible for making the path of light visible?
Q2. Give an example of a phenomenon where Tyndall effect can be observed.
Q3. What is the function of retina in the human eye?
Q4. What is iris? What is its function?
Write the function of iris in the human eye.
Q5. What is a pupil?
Q6. What kind of lens is used in the spectacles of a person suffering from myopia (near – sightedness)?
Q7. To an astronaut why does the sky appear dark instead of blue?
Q8. What is meant by power of accommodation of the eye?
Q9. Which liquid fills the space between eye lens and retina?
Q10. What is meant by least distance of distinct vision?
QUESTIONS: (2 marks each)
Q1. Draw a ray diagram to show the refraction of light through a glass prism. Mark on it
(a) the incident ray
(b) the emergent ray
(c) the angle of deviation.
Q2. State the factors on which the colour of scattered light perceived by us depends.
Q3. When ciliary muscles of a normal eye is in most contracted state. Explain with reason.
If the ciliary muscles of a normal eye are in their
(a) most relaxed state.
(b) most contracted state.
Mention in brief how focal length and power of eye lens will change in both the cases. Give reason for your answer.
Q4. Name the part of eye where images formed in a normal human eye. State how the image position changes in myopia and hypermetropia.
Q5. A person suffering from an eye – defect uses lenses of power -1D to correct the defect. Name the defect is suffering from and the nature of lens to be used to correct it.
Q6. A person is able to see objects clearly only when these are lying at distances between 50 cm and 300 cm from his eye. Identify the kind of defect of vision he is suffering from. Give reason for your answer.
Q7. Draw a neat diagram to show the refraction of a light ray through a glass prism, and label on it the angle of incidence and angle of deviation.
Q8. What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue or the sun appears reddish at sunrise.
Q9. What is meant by spectrum? How can we combine the components of white light after a prism has separated them?
Q10. Write approximate wavelengths for (i) blue and (ii) red light. Which colour has the higher speed in vacuum? Which colour has the higher speed in glass?
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