Track quiz
Here are the rules first. Each lab uses these exact words.
| Idea | The rule |
|---|---|
| The eye is a lens | Light enters through the cornea. The lens forms a real, upside-down image on the retina. The optic nerve carries the signal to the brain. |
| Focusing near and far | The eye lens changes shape to focus. Ciliary muscles relax for far objects and contract for near ones. The nearest sharp distance is the near point, about 25 cm. |
| Far things blur | In myopia, distant objects focus in front of the retina. A concave lens fixes it. The lens must put far objects at the far point. |
| Near things blur | In hypermetropia, near objects focus behind the retina. A convex lens fixes it. The lens puts a 25 cm object's image at the near point. |
| The eye with age | With age, the near point moves farther away. A convex lens helps with reading. A bifocal lens has a concave top, for far. Its bottom is convex, for near. |
| Light comes apart | A prism splits white light into seven colours. Violet bends the most and red bends the least. This splitting is called dispersion. |
| Sky is blue | Air scatters short waves like blue more than long waves like red. The scattered blue light makes the sky look blue. With no air, the sky would look dark. |
| Sun at the edge of the day | Near the horizon, sunlight crosses much more air. More blue scatters out. The red light that is left makes the Sun look red. |
Where does a far tree's image form in a normal eye?
A person looks from a far tree to a near book. What do the ciliary muscles do?
A myopic eye has a far point of 20 cm. What lens power fixes it?
An eye has a near point of 50 cm. What lens lets it read at 25 cm?
An older person's eye lens gets stiffer. What happens to the near point?
White light crosses a prism. Which colour bends the least?
A small moon has no air. How does its daytime sky look?
Why is the Sun red at sunset?
At night, one point of light flickers and another shines steadily. Which is more likely a planet?
Open Chapter 10 of your Class 10 Science book. It is The Human Eye and the Colourful World. Check its pictures against what you have seen here.
The next chapter is Electricity.