pupil
retina
ciliary muscles
iris
The relaxation or contraction of ciliary muscles changes the curvature of the eye lens. The change in curvature of the eye lens changes the focal length of the eyes. Hence, the change in focal length of an eye lens is caused by the action of ciliary muscles.
So, the correct answer is option (C): ciliary muscles.
Match Column-I with Column-II and choose the correct option:
| Column-I (Minerals) | Column-II (Features) | ||
|---|---|---|---|
| A. | Copper | (i) | Used in manufacturing of steel and plants |
| B. | Bauxite | (ii) | Used in electric and electronic industries |
| C. | Mica | (iii) | Used in electric cables and utensils |
| D. | Manganese | (iv) | Used in aluminium production |
Choose the correct answer from the options given below:
Give reasons:
(i) The sky appears dark to passengers flying at very high altitudes.
At very high altitudes, passengers are above the atmosphere where there is less scattering of sunlight. As a result, they do not see the scattered blue light and the sky appears dark, similar to the condition experienced by astronauts in space.
(ii) 'Danger' signal lights are red in color.