Question

rani is unable to see the letters written on white board from back bench which defect she is suffering from
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Answer 1

Myopia

• Myopia, also known as near-sightedness or short-sightedness is the defect of the eye in which a person can only see those objects or letters written quite near to them. They would not be able to view things that are far away from them.
• Rani is also suffering from this defect.
• Concave glasses or contact lenses of correct focal length can be used to correct this defect.

Causes of Myopia

• Hereditary means
• Straining of eyes
• Diabetes
• Over usage of electronic gadgets

Formula to obtain lens with the required focal length:

$\frac{1}{f} = \frac{1}{f1} +\frac{1}{f2}$

Here,

• f1 refers to the required focal length of the lens.
• f2 refers to the focal length of the lens affected by myopia.
• f refers to the effective focal length of the that can be used to correct the vision.