(a) A student is unable to see clearly the words written on the blackboard placed at a distance of…
(a) A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from State the possible causes of this defect and explain the method of correcting it.
(b) Why do stars twinkle? Explain.
Solution
(a) Defects of vision: Myopia or short sightedness. Reasons: Excessive curvature of eye lens and elongation of eye ball. Correction: Using a concave lens myopic
(b) Due to atmospheric refraction stars twinkle. The density of atmospheric layers keep changing due to which point sized star sometimes appear brighter or dimmer with changing position. Due to this, stars appears twinkling.
