CBSE Class 6 Science Notes Chapter 11 Light, Shadows and Reflection

Learn from School Connect Online in this chapter we will learn about Light,Shadows and Reflection,Light Shadows and Reflection Class 6 Notes Science Chapter 11

Light is a form of energy which helps us in seeing objects. When light falls on an object, some of the light gets reflected. The reflected light comes to our eyes and we are able to see an object.

The different topics covered in CBSE Class 6 Science Chapter 11 are tabulated below:

Ex : 11.1 –  Transparent, Opaque and Translucent Objects

Light, or Visible Light, commonly refers to electromagnetic radiation that can be detected by the human eye.An object which emits light, is called a source of light.

For example : sun, torch, etc.

Ray of light: A straight thin beam of light from a source to an object is called a ray of light.

Luminous and Non-luminous objects :

Luminous Objects/Bodies

1. Luminous objects/bodies are Objects/bodies that do not give out or emit light of their own.
2. Luminous objects can cause the sensation of light.
3. Luminous objects are visible as they emit light of their own.
4. Examples of luminous objects include: Sun, Stars, Candle, Oil lamp, Torch, Electrical bulb, Glowing insects, tube light etc.

Non-luminous Objects/Bodies

1. Non-luminous objects/bodies are bodies/objects that do not give out or emit light of their own.
2. Non-luminous objects do not cause the sensation of light.
3. Non-luminous objects are visible because of luminous objects.
4. Examples of non-luminous objects/bodies include: Earth, Moon, Piece of cloth, Coal, Table, Chair, Eraser, Pen, Pencil etc

Translucent objects: Some objects allow only a part of light falling on them to pass through, such objects are called translucent objects. For example, a single thin sheet of paper.

Transparent objects: Those objects which allow all the light to pass through them are called transparent objects.

Opaque objects: If an object completely stops the passage of all the light falling on it, it is an opaque object.

Ex : 11.2 –  What Exactly Are Shadows?

• A shadow is formed when an opaque object comes in the path of light.
• A shadow needs a screen where it is formed, for example, the ground, or walls of a room or even the surfaces of buildings.
• Shadows give us an idea about the shapes of different objects. Or, it can even mislead us about the shape of different objects. E.g. the shadow of a cone appears to be a triangle on the screen.

Ex : 11.3 –  A Pinhole Camera

A Pinhole camerais a device which forms a photograph-like image of a bright object on a screen.

Formation of image by pinhole camera

• A pinhole camera is a simple camera that consists of a light-proof box, a thin film for a screen and a small aperture or hole to allow the passage of light rays.
• The light from outside enters through the small hole and forms an image on the screen that is inverted.

Ex : 11.4 –  Mirrors and Reflections

Mirrors :

A smooth shining surface, which rebounds the light back in the same or in different directions is called a mirror.

Reflection :

The process through which light rays falling on the surface on an object are sent back is called reflection of light. Thus, when light falls on the surface of an object it sends back the light.

Characteristics of images

• Images have colour, unlike shadows. They are formed due to the converging rays of light that come after reflecting from objects.
• A real image is formed by actual convergence of light rays. Real images always form on a screen.
• A virtual image is the apparent convergence of diverging light rays. Virtual images cannot be obtained on a screen.

Plane mirrors and images formed by them

Plane mirrors are simply flat mirrors without curves.Because plane mirrors can be found almost anywhere, the average person is incredibly familiar with them (even if they don’t know the technical term). While the first manmade mirrors were made from intensely polished bronze, silver and other metals.

To see any image in the mirror a person should be in the line of sight of the mirror, as when the person is in the line of sight of the mirror then the reflected ray reaches that person’s eye through which anyone can see the image of the object if they are in the line of sight of the mirror, this is because light has the property of moving in a straight line.

The important phenomenon of the plane mirror is that the reactions of the objects form the virtual image with the same magnification, size, and distance of the same as the object really are.

Conclusion :

• Source of light: An object that gives out light (luminous object) is called a source of light.
• Transparent material: A material that transmits all the light is called a transparent material.
• Translucent material: A material that transmits some amount of light is called a translucent material.
• Opaque material: A material that completely blocks the light is called an opaque material.
• Shadow: An area of darkness formed by an opaque object obstructing light is called a shadow.
• Objects can be transparent, translucent, or opaque, depending on how much light can pass through them.
• A shadow is formed when an opaque object blocks the light falling on it.
• A shadow is always black regardless of the colour of the object.
• We say light is reflected when it bounces off a surface.
• A rough and bumpy surface reflects light in different directions.
• A smooth surface reflects light in only one direction.
• An image shows the colour, outline, and details of the object.

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