$A$ man wearing glasses of focal length $+1\, m$ cannot see objects beyond $1\, m$. What is the defect in his eye?

$(a)$ Explain the phenomenon of scattering of light. State the factor on which the colour of scattered light depends.
$(b)$ List any two natural phenomena based on the scattering of light.

$A$ person is able to see objects clearly only when these are lying at distances between $50 \text{ cm}$ and $300 \text{ cm}$ from his eye. Identify the kind of defects of vision he is suffering from. Give reason for your answer.

Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?

When one enters a dim-lit room from bright light,one is unable to see the objects in the room for some time. Explain why.

What is the time difference between the actual sunset and the apparent sunset?