Science Olympiad Test: Human Eye and Colorful World- 2 - Class 10 MCQ

At noon because the sun is overhead, the light is scattered the least and hence appears white. When it is overhead, it has lesser air to travel through and the scattering from dust and other particles is reduced if the distance to be travelled in air is reduced.

A rainbow is consistently positioned in the opposite direction of the Sun, a phenomenon attributed to water droplets functioning as miniature prisms. These droplets refract and disperse sunlight upon impact, followed by internal reflection and, ultimately, refraction as the light exits the raindrop. This intricate process results in the dispersion of light and internal reflection, causing diverse colors to be visible to the observer.

The focal length of the eye lens increases when eye muscles relaxed and becomes thinner. The sharp image of the distant object is formed at the retina. This enables us to focus accurately on distant objects.

• Two times a ray of light undergo refraction when it passes through a water droplet.
• One time at air-water interface and one time at water-air interface.

A = 60°, ∠i= ∠e = 40°
As A + D = i + e
∴ 60° = D = 40° + 40° ⇒ D = 80° – 60° = 20° 

Violet light has higher refractive index than the red light.
Thus, the focal length for red light is greater. 
This means that the red light has lower tendency to get refracted than the violet light.

The splitting up of white light into seven colours on passing through a transparent medium like a glass prism is called dispersion of light.
Cause of dispersion of light: When light passes through a prism, the different frequencies of light travel at different velocities. Because of refraction, the different velocities make the angles of refraction different, causing the light to travel in slightly different directions.
The diagram demonstrating the dispersion of white light by a glass prism is shown:

Advanced sunrise phenomenon and is not explained on the basis of scattering of light. In our planet earth, we often witness advanced sunrise and even advanced sunset. So, the main reason behind the advanced sunrise is the refraction. The scattering of light rays, has no role behind the occurrence of this phenomenon.

Relation between angle of incidence and angle of emergence:
i + e = A + D
where i = is the angle of incidence 
e =  is the angle of emergence
A = is Prism Angle
D = is deviation angle
when angle of incidence is equals to angle of emergence (i = e) then prism will be in the minimum deviation position.

The prism can be seen as the roof top of a hut as shown in the figure.

Gases and particles in Earth's atmosphere scatter sunlight in all directions. Blue light is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

• The angle of incidenc: As the angle of incidence increases, first the angle of deviation decreases and reaches to a minimum value for a certain angle of incidence. By further increasing the angle of incidence, the angle of deviation is found to increase.
• The material of prism (i.e., on refractive index): For a given angle of incidence, the prism with a higher refractive index produces a greater deviation than the prism which has a lower refractive index.
• Angle of prism: Angle of deviation increases with the increase in the angle of prism.

The crystalline lens of some people in old age becomes hazy or even opaque. This happens because of the development of a membrane over it when it happens the person is said to have a cataract.

Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes(e.g. the human eye). They are responsible for color vision and they function best in relatively bright light.

The ciliary muscles change the focal length of the eye lens to focus objects at variable distances.