LIGHT | Class 8 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 3 min read
LIGHT – this guide gives you a concise, exam-ready overview of LIGHT from Class 8 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
13.8 Care of the Eyes
Proper care of the eyes is essential to maintain good vision and prevent eye problems. Eyes should be protected from too little or too much light, as insufficient light causes eyestrain and headaches, while excessive light, such as direct sunlight or laser beams, can damage the retina. One should never look directly at the Sun or powerful lights. Avoid rubbing eyes, and if dust enters, wash with clean water and consult a doctor if irritation persists. Reading should be done at a comfortable distance (about 25 cm) to avoid strain. A balanced diet rich in vitamin A is crucial for eye health; deficiency can cause night blindness and other issues. Foods like carrots, green leafy vegetables, eggs, milk, and fruits like papaya and mango are good sources of vitamin A. Regular eye checkups and using prescribed spectacles help maintain eye health. This section also highlights how animals have different eye structures adapted to their environments, such as the compound eyes of butterflies and the large pupils of night birds like owls.
📊 Diagram: Fig. 13.17: Eyes of a butterfly
🔗 Connection: This section prepares for understanding how visually impaired persons read and write, leading to the next section on aids for visually impaired persons.
Frequently asked questions
1. Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.
In a dark room, you cannot see objects inside the room because there is no light to reflect from those objects to your eyes. However, if there is light outside the room and you look through a window or door, you may see objects outside because light from those objects can enter the room and reach your eyes.
2. Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?
Regular reflection occurs when light rays fall on a smooth and polished surface and reflect in a definite direction, producing a clear image. Diffused reflection occurs when light rays fall on a rough surface and reflect in many directions, so no clear image is formed.
No, diffused reflection does not mean the failure of the laws of reflection. The laws of reflection hold for each individual ray even in diffused reflection; it is just that the surface irregularities cause the reflected rays to
3. Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case. (a) Polished wooden table (b) Chalk powder (c) Cardboard surface (d) Marble floor with water spread over it (e) Mirror (f) Piece of paper
(a) Polished wooden table - Regular reflection because the surface is smooth and polished. (b) Chalk powder - Diffused reflection because the surface is rough and powdery. (c) Cardboard surface - Diffused reflection due to its rough texture. (d) Marble floor with water spread over it - Regular reflection because water makes the surface smooth. (e) Mirror - Regular reflection as it has a very smooth and polished surface. (f) Piece of paper - Diffused reflection because paper surface is rough.
4. State the laws of reflection.
The laws of reflection are: 1. The incident ray, the reflected ray and the normal to the surface at the point of incidence all lie in the same plane. 2. The angle of incidence is equal to the angle of reflection.
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