What is near-sightedness?

Sometimes you see a person reading the newspaper by placing it very close to his eyes. Which defect is he suffering from? How can the defect be removed?

$A$ narrow beam $PQ$ of white light is passing through a glass prism $ABC$ as shown in the diagram.
Trace it on your answer sheet and show the path of the emergent beam as observed on the screen $DE$.
$(i)$ Write the name and cause of the phenomenon observed.
$(ii)$ Where else in nature is this phenomenon observed?
$(iii)$ Based on this observation,state the conclusion which can be drawn about the constituents of white light.

What is the central aperture of the eye located behind the cornea called?

Which of the following two colors are complementary colors?

Mention the factor on which scattering of light depends. Why does the sky appear dark in space?