Light plays a vital role in everyday life and is one of the most important topics in TNPSC General Science. This TNPSC Physics Light Quiz covers essential TNPSC Physics Questions on reflection, refraction, spherical mirrors, lenses, image formation, and common optical phenomena. Practising these Light Physics MCQs helps you understand how light behaves in different situations while improving your ability to solve TNPSC General Science Light Questions accurately in the examination.
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TNPSC Physics Light Quiz 4 – Detailed Explanations
The explanations in this TNPSC Physics Light Quiz focus on the scientific principles behind each answer. Instead of memorizing facts, you’ll learn why reflection follows specific laws, how refraction changes the path of light, and how mirrors and lenses form images. Reviewing these TNPSC Physics Questions and Light Physics MCQs will strengthen your understanding of concepts frequently tested in TNPSC examinations.
1. The coloured part of the human eye is called:
Answer: Iris
Explanation:
The iris is the coloured circular muscle of the human eye that surrounds the pupil. It controls the amount of light entering the eye by adjusting the size of the pupil. In bright light, the iris makes the pupil smaller, while in dim light, it enlarges the pupil to allow more light into the eye.
Quick Revision
- The iris is the coloured part of the eye.
- It surrounds the pupil.
- It regulates the amount of light entering the eye.
- It works by changing the size of the pupil.
Real-Life Example:
When you move from a dark room into bright sunlight, your iris automatically reduces the size of the pupil to protect the retina from excessive light.
2. The opening through which light enters the eye is the:
Answer: Pupil
Explanation:
The pupil is the opening at the centre of the iris through which light enters the eye. Its size changes automatically to regulate the amount of light reaching the retina.
Quick Revision
- Central opening of the iris.
- Allows light to enter the eye.
- Becomes smaller in bright light and larger in dim light.
Real-Life Example:
Your pupils enlarge in a dark room to allow more light into the eye.
3. The image in the human eye is formed on the:
Answer: Retina
Explanation:
The retina is the light-sensitive layer at the back of the eye where a real and inverted image is formed. It converts light into nerve signals that are sent to the brain.
Quick Revision
- Image is formed on the retina.
- Light-sensitive layer of the eye.
- Connected to the optic nerve.
Real-Life Example:
The retina functions like the image sensor in a digital camera.
4. The transparent front portion of the eye is known as the:
Answer: Cornea
Explanation:
The cornea is the transparent outer layer of the eye. It protects the eye and bends incoming light before it reaches the lens.
Quick Revision
- Transparent front surface.
- Protects the eye.
- Begins the refraction of light.
Real-Life Example:
The cornea acts like the front glass of a camera, allowing light to enter clearly.
5. The ability of the eye lens to adjust its focal length is called:
Answer: Accommodation
Explanation:
Accommodation is the ability of the eye lens to change its shape with the help of ciliary muscles so that both nearby and distant objects can be seen clearly.
Quick Revision
- Changes the focal length of the eye lens.
- Controlled by ciliary muscles.
- Helps focus objects at different distances.
Real-Life Example:
Your eyes automatically adjust when you look from a book to a distant object.
6. Myopia is commonly known as:
Answer: Short-sightedness
Explanation:
Myopia is a vision defect in which nearby objects are seen clearly, but distant objects appear blurred because the image forms in front of the retina.
Quick Revision
- Nearby objects are clear.
- Distant objects appear blurred.
- Corrected using a concave lens.
Real-Life Example:
A student can read a notebook easily but cannot clearly see the writing on the classroom board.
7. Myopia is corrected using a:
Answer: Concave Lens
Explanation:
A concave lens diverges incoming light rays so that the image forms on the retina, allowing distant objects to be seen clearly.
Quick Revision
- Diverging lens.
- Corrects myopia.
- Helps focus distant objects.
Real-Life Example:
People with short-sightedness wear spectacles fitted with concave lenses.
8. Hypermetropia is commonly known as:
Answer: Long-sightedness
Explanation:
Hypermetropia is a vision defect in which distant objects are seen clearly, but nearby objects appear blurred because the image forms behind the retina.
Quick Revision
- Nearby objects appear blurred.
- Distant vision is usually clear.
- Corrected using a convex lens.
Real-Life Example:
A person may hold a book farther away to read comfortably.
9. Hypermetropia is corrected using a:
Answer: Convex Lens
Explanation:
A convex lens converges incoming light rays so that the image forms on the retina, helping people see nearby objects clearly.
Quick Revision
- Converging lens.
- Corrects hypermetropia.
- Used for near vision correction.
Real-Life Example:
Reading glasses often use convex lenses to improve near vision.
10. Which part of the eye sends visual information to the brain?
Answer: Optic Nerve
Explanation:
The optic nerve carries electrical signals from the retina to the brain, where they are interpreted as images.
Quick Revision
- Connects the eye to the brain.
- Transmits visual impulses.
- Essential for vision.
Real-Life Example:
Even if the retina forms an image correctly, damage to the optic nerve can affect vision.
11. Which instrument is used to observe distant celestial objects?
Answer: Telescope
Explanation:
A telescope is an optical instrument used to observe distant objects such as stars, planets, and galaxies. It uses lenses or mirrors to collect and magnify light, making faraway objects appear larger and clearer.
Quick Revision
- Used to observe distant celestial objects.
- Works using lenses or mirrors.
- Commonly used in astronomy.
Real-Life Example:
Astronomers use telescopes to study the Moon, planets, and distant stars.
12. Which optical instrument is used to observe tiny objects?
Answer: Microscope
Explanation:
A microscope is an optical instrument that magnifies very small objects, allowing details that cannot be seen with the naked eye to become visible.
Quick Revision
- Magnifies tiny objects.
- Uses one or more lenses.
- Commonly used in laboratories.
Real-Life Example:
A biology student uses a microscope to observe plant and animal cells.
13. A periscope works mainly on the principle of:
Answer: Reflection
Explanation:
A periscope works on the principle of multiple reflection. It uses two plane mirrors or right-angled prisms placed at 45° to reflect light, allowing objects that are not in the direct line of sight to be viewed.
Quick Revision
- Based on the principle of reflection.
- Uses two plane mirrors or prisms.
- Mirrors are usually placed at 45°.
Real-Life Example:
Soldiers and submarine crews use periscopes to observe objects while remaining protected.
14. Which optical device is commonly used by submarines?
Answer: Periscope
Explanation:
A periscope enables people inside a submarine to observe objects above the water surface without exposing the submarine. It works using the principle of reflection.
Quick Revision
- Used in submarines.
- Helps observe objects above water.
- Operates using reflection.
Real-Life Example:
A submarine crew raises the periscope to check nearby ships while staying underwater.
15. The eye lens becomes less flexible with age, leading to:
Answer: Presbyopia
Explanation:
Presbyopia is an age-related vision defect caused by the gradual loss of flexibility of the eye lens. As a result, focusing on nearby objects becomes difficult.
Quick Revision
- Age-related eye defect.
- Eye lens loses flexibility.
- Difficulty seeing nearby objects.
Real-Life Example:
Many older adults hold newspapers farther away to read the text clearly.
16. Which type of lens is commonly used to correct presbyopia?
Answer: Bifocal Lens
Explanation:
A bifocal lens contains two optical powers in a single lens, helping people with presbyopia see both nearby and distant objects clearly without changing spectacles.
Quick Revision
- Corrects presbyopia.
- Has two different lens powers.
- Used for both near and distant vision.
Real-Life Example:
An elderly person can read a book and watch television using the same pair of bifocal glasses.
17. The human eye forms an image that is:
Answer: Real and Inverted
Explanation:
The eye lens forms a real and inverted image on the retina. The brain processes these signals and interprets the image in the correct upright orientation.
Quick Revision
- Image is real.
- Image is inverted.
- Formed on the retina.
Real-Life Example:
Like a camera, the eye forms an inverted image, but the brain allows us to perceive the world upright.
18. Which part of the eye controls the size of the pupil?
Answer: Iris
Explanation:
The iris is a muscular structure that adjusts the size of the pupil according to the surrounding light conditions, ensuring the right amount of light enters the eye.
Quick Revision
- Controls pupil size.
- Regulates light entering the eye.
- Contracts and relaxes automatically.
Real-Life Example:
When you step outdoors on a sunny day, the iris quickly reduces the size of the pupil.
19. Which eye defect makes distant objects appear blurred?
Answer: Myopia
Explanation:
Myopia is a vision defect in which distant objects appear blurred because the image forms in front of the retina. It is commonly corrected using a concave lens.
Quick Revision
- Also called short-sightedness.
- Distant objects appear blurred.
- Corrected with a concave lens.
Real-Life Example:
A person with myopia may clearly read a mobile phone but struggle to recognize a distant signboard.
20. Which part of the eye acts like a screen where the image is formed?
Answer: Retina
Explanation:
The retina acts as the light-sensitive screen of the eye. It receives the image formed by the eye lens and converts it into nerve impulses that are sent to the brain through the optic nerve.
Quick Revision
- Light-sensitive screen of the eye.
- Receives the image formed by the lens.
- Sends visual signals to the brain.
Real-Life Example:
Just as a camera sensor captures an image, the retina captures the image before the brain processes it.
Further Reading:
More understanding after completing this TNPSC Physics Light Quiz, explore the official NCERT chapter The Human Eye and the Colourful World. It explains the structure of the human eye, image formation, accommodation, common vision defects, and their correction in a clear and systematic manner. For additional practice, you can also solve the NCERT Exemplar – Light questions to reinforce key concepts.
Official NCERT Resources:
