The Human Eye and the Colourful World
Subject: General Science
Sample Practice Questions
Question 1: What is the phenomenon of splitting of white light into its component colours called?
- Refraction
- Reflection
- Dispersion
- Scattering
Explanation: The splitting of light into its component colours is called dispersion. A prism disperses white light into its seven-colour components.
Question 2: What is the angle between the two lateral faces of a prism called?
- Angle of incidence
- Angle of refraction
- Angle of the prism
- Angle of deviation
Explanation: The angle between the two lateral faces of a prism is called the angle of the prism. It determines the amount of deviation of light passing through the prism.
Question 3: Which colour of light bends the most when passing through a prism?
- Red
- Orange
- Yellow
- Violet
Explanation: Violet light bends the most while passing through a prism. This is because violet light has the shortest wavelength and is deviated the most.
Question 4: What causes the formation of a rainbow?
- Reflection of sunlight by clouds
- Dispersion of sunlight by tiny water droplets
- Scattering of light by air molecules
- Refraction of light by the atmosphere
Explanation: A rainbow is caused by dispersion of sunlight by tiny water droplets present in the atmosphere. The water droplets act like small prisms, refracting and dispersing light.
Question 5: What happens when a second inverted prism is placed in the path of the dispersed light?
- It disperses the light further
- It recombines the colours to form white light
- It absorbs all colours
- It reflects the light
Explanation: When a second identical prism is placed in an inverted position with respect to the first prism, it recombines all the colours of the spectrum to form white light. This was demonstrated by Newton.
Question 6: Where is the image formed in the human eye?
- Cornea
- Iris
- Pupil
- Retina
Explanation: The eye lens forms an inverted real image of the object on the retina. The retina is a delicate membrane having light-sensitive cells that generate electrical signals.
Question 7: Why are danger signal lights red in colour?
- Red light is easily visible
- Red light is scattered the least by fog or smoke
- Red light is scattered the most
- Red light has the shortest wavelength
Explanation: Danger signal lights are red because red light is scattered the least by fog or smoke. Therefore, it can be seen from a distance even in adverse weather conditions.
Question 8: What is the far point of a normal human eye?
- 25 cm
- 50 cm
- Infinity
- 1 m
Explanation: The farthest point up to which the eye can see objects clearly is called the far point of the eye. For a normal eye, it is infinity.
Question 9: What is the condition called when the crystalline lens becomes milky and cloudy at old age?
- Myopia
- Hypermetropia
- Presbyopia
- Cataract
Explanation: Cataract is the condition where the crystalline lens becomes milky and cloudy at old age. This causes partial or complete loss of vision but can be restored through surgery.
Question 10: What causes the dispersion of white light into its component colours?
- Reflection of light
- Refraction of light through a prism
- Scattering of light
- Diffraction of light
Explanation: The splitting of white light into its component colours is called dispersion. Different colours of light bend through different angles as they pass through a prism, causing them to separate.