NCERT Solutions for Class 8 Science, Chapter 16 - Light

The NCERT Class 8 Science, Chapter 16 deals with light and reflection. Our eyes alone cannot see any object. It is possible only when light reflected from an object enters our eyes. The light by which we can see an object may have been emitted by the object; the ray of light which falls on a mirror is called incident ray, and the ray which comes back from the surface of a mirror after reflection is known as the reflected ray. A perpendicular line at a point of incidence is called normal.  As you move further in the chapter you will learn regular reflection and diffused/irregular reflection that takes place from rough surfaces.

To know more about NCERT Solutions for Class 8, Science Chapter 16 – Light, let’s look at the topics and sub-topics of this chapter:

16.1  What makes Things Visible

16.2  Laws of Reflection

16.3  Regular and Diffused Reflection

16.4  Reflected Light Can be Reflected Again

16.5  Multiple Images

16.6  Sunlight – White or Coloured

16.7  What is inside Our Eyes?

16.8  Care of the Eyes

16.9  Visually Impaired Persons Can Read and Write

16.10 What is the Braille System?

In Class 8 Science Chapter 16, you will learn-

Section 16.1 – Why the objects are visible? This section gives you the answer. We cannot see the objects in the dark because eyes alone cannot see the objects. It is only when light from an object enters our eyes then only we are able to see the objects. The light may have been emitted by the object or may have been reflected by it.

Section 16.2 – This section basically deals with the laws of reflection. At first, you will be introduced with the incident ray (the ray of light which falls on a mirror ), reflected ray ( the ray which comes back from the surface of a mirror after reflection ) and normal (a perpendicular line at a point of incidence). As you move further in this section you will study the two laws of reflection through several practical examples that will make this concept easier to understand.

Section 16.3 – In this section, you will study regular and diffused/irregular reflection. When all the parallel rays reflected from a rough or irregular surface are not parallel, the reflection is known as diffused or irregular reflection. Remember that the diffused reflection is not due to the failure of the laws of reflection. It is caused by the irregularities in the reflecting surface, like that of cardboard. On the other hand, reflection from a smooth surface like that of a mirror is called regular reflection.

Section 16.4 – This section deals with the property of light that reflected light can be reflected again. Recall the last time you visited a hairdresser. He makes you sit in front of a mirror. After your haircut is complete,  he holds a mirror behind you to show you how the hair has been cut. Do you know how you could see the hair at the back of your head? This is because the light reflected from the mirror which is placed in front of you is again reflected from the second mirror which is in the hands of the hairdresser.

Section 16.5 – Now you are aware that a mirror (plane mirror) forms only a single image of an object. What happens if two plane mirrors are used in combination? This section gives you the answer. As we have studied in the previous section that reflected light can be reflected again. So if we are placing two mirrors in front of each other then the reflected ray of light keeps on reflecting and infinite images will be made.

Section 16.6 – You have studied in class VII that the sunlight is referred to as white light. Now you will learn that the sunlight consists of seven colours through an interesting activity. Take a mirror of the appropriate size and place it against the sunlight and use a sheet of paper to observe the reflected light. You will be able to see seven colours on the sheet of paper.

Section 16.7 – This sections teach you what is inside our eyes. We are able to see only those objects which are reflecting the ray of light. Eye is one of our most important sense organs. This section will brief you on the overall structure of the human eye with the essential parts like cornea, iris, pupil, and retina. At the junction of the optic nerve and the retina, there are no sensory cells, so no vision is possible at that spot. This is called the blind spot.

Section 16.8 – In this section, you will learn how to take care of your eyes. You should take care of your eyes on a regular basis. If there is any problem you should go to an eye specialist.

Using suitable spectacles, avoiding too much or too little light, not looking at a powerful light or the sun, reading at the normal distance for vision are some of the measures that you can take for the care of your eyes.

Section 16.9 – Towards the end of the chapter this section will teach you how a visually impaired person can read or write. Some people have very limited vision to see things and few of them cannot see at all since birth. Vision can also be lost as a result of some disease or injury. Such persons can identify things by touching and listening to voices carefully. Their senses will develop more sharply than other people. Additional resources like Braille System can be used to develop their capabilities further which you will study in the last section of this chapter.

Section 16.10 – In this section, you will study what is the Braille System and why it is used. Louis Braille who was himself a visually challenged person developed a system for visually impaired persons and published it in 1821. Several Braille codes were made for common languages, mathematics, and scientific notations. Many Indian languages can be read using the Braille System.

To know more about the NCERT solutions Class 8 Science, Chapter 16 – Light explore the activities below: