Human Eye and C...

To read a poster on a wall, a person with defective vision needs to stand at a distance of $$0.4m$$ from the poster. A person with normal vision can read the poster from a distance of $$2.0m$$. Which one of the following lens may be used to correct the defective vision?

Rainbow is produced when sunlight falls on drops of rain, Which of the following physical phenomena are responsible for this? 

If the power of an eye lens increases, then the defect of vision so produced is known as

A mirage is observed when

Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena is/are responsible for this?

The middle vascular coat that darkens the eye chamber and prevents refraction by absorbing the light rays is

The sky appears blue, due

Which of the following statements is correct about rainbow?

A normal eye is not table to see objects closer than $$25$$cm because.

The spread in colours in a rainbow on sky is primarily due to