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Question
What is meant by optical illusion? Give one example.
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Solution
An optical illusion is the life-like continuous movement on the screen. Television is an example of optical illusion, where the scanning beam of a picture frame of the TV camera moves so rapidly on the viewing screen of the TV set that our eyes cannot keep pace with it.
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Have a look at the posture of this girl who is reading a book and answer the questions which follow:
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- Name the problem she is facing.
- What are the two conditions shown in sections A and B of the eye as applicable to her.
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| A | B |



