What happens to the lens and the ciliary muscles when you are looking at distant objects?

The brilliance of a diamond is due to which phenomenon?

Due to atmospheric refraction of light,the Sun appears to rise $................$ its actual sunrise.

$(i)$ Write the range of distance for a person having normal vision.
$(ii)$ $A$ person needs to use glasses for reading a newspaper. Identify the defect in his vision and the type of lens he would need to correct it.
$(iii)$ Sometimes when we enter into a dark room from bright sunlight,we are unable to see objects clearly. Why?

$(a)$ Explain with the help of a labelled diagram how a combination of two prisms can be used so that incident white light emerges out of the second prism as white light.
$(b)$ Name the scientist who first performed this activity.
$(c)$ Explain the term spectrum in brief.

Sometimes you see a person reading the newspaper by placing it far away from their eyes. Which defect is the person suffering from? How can this defect be corrected?