Give one cause of long-sightedness (hypermetropia).

Is the position of a star as seen by us its true position? Justify your answer.

Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence,define the angle of deviation.

$(a)$ How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?
$(b)$ State any two effects of atmospheric refraction on the sun as observed from the Earth.

$A$ beam of white light falling on a glass prism gets split up into seven colours marked $1$ to $7$ as shown in the diagram.
$(a)$ The colours at positions marked $3$ and $5$ are similar to the colour of the sky and the colour of gold metal respectively. Is the above statement made by the student correct or incorrect? Justify.
$(b)$ Which of the above shown positions corresponds approximately to the colour of:
$(i)$ a brinjal
$(ii)$ danger signal
$(iii)$ neel (indigo) which is applied to clothes
$(iv)$ orange

On what factor does the colour of the scattered light depend?