These DAV Class 6 Science Notes and DAV Class 6 Science Chapter 12 Notes – Light and Shadows act as excellent revision resources, particularly in preparation for board exams.
Light and Shadows Class 6 DAV Notes
→ Light: Light is a source of energy which produces the sensation of sight in our eyes.
→ Natural Sources of Light: The sun and the stars emit their own light. They are called natural sources of light.
→ Artificial Sources of Light: Man has developed a number of sources of light; such as bulb and tubelight. These are called artificial sources of light.
→ Propagation of Light: Light always travels in a straight line.
→ Transparent Object: An object which allows light to pass through it is called transparent object, e.g. glass sheet, water and some types of plastic.
→ Translucent Object: An object which allows light to pass through it partially is called translucent object, e.g. butter paper, oil, etc.
→ Opaque Object: An object which does not allow light to pass through it is called opaque object, e.g. cardboard, wood, metal, etc.
→ Shadow: When an opaque object comes in the path of hght, a dark region is formed on a screen which is kept behind the object. This dark region or patch is called shadow.
→ Three required things for the formation of shadow:
- A source of light
- An opaque object
- A screen (ground/wall) to obtain the shadow.
→ Characteristics of Shadow
1. The size of the shadow depends on the distance between the source of high and the opaque object.
2. Shadow of an opaque object is always black, irrespective of the colour of the object.
→ Solar Eclipse: When the moon comes between the sun and the earth, it casts a shadow on the earth. This shadow can fully or partially block the view of the sun. This phenomenon is called solar eclipse. A solar eclipse happens on a new moon day.
→ Lunar Eclipse: When the earth comes between the sun and the moon, the earth casts its shadow on the moon. This phenomenon is called lunar eclipse. Lunar eclipse happens on a full moon day.
→ Pinhole Camera: Pinhole camera is a simple application of the linear propagation of light. This can be made by using a cylindrical or rectangular box. At one of the walls of the box, pin-sized hole is made; which allows the light to go inside the ‘camera’. On the opposite wall, a translucent screen is placed; on which image is formed. You can make simple pin-hole camera and view the images of distant objects formed on it.
→ Reflection of Light: When light falls on a shining surface, there is a change in its direction of travel. This phenomenon is called reflection of light.
→ Regular Reflection: When light falls on a smooth and shining surface; most of the light is reflected back. This is called regular reflection.
→ Irregular Reflection: When light falls on a rough and shining surface; the reflection is somewhat diffused. This is called irregular or diffused reflection.
→ Properties of Image formed by plane mirror:
- The image is formed as far behind the mirror as the object is in front of it.
- Image is erect and is of the same size as object.
- The image cannot be obtained on a screen. Such type of image is called virtual image.
- Image is laterally inverted.
→ Light: It is a form of energy which gives our eyes the sense of vision.
→ Luminous Object: An object which produces its own light.
→ Non-luminous Object: An object which does not produce its own light.
→ Transparent: If light can completely pass through an object, the object is called transparent.
→ Translucent: If light can partially pass through an object, the object is called translucent.
→ Opaque: If light cannot pass through an object, the object is called opaque.
→ Shadow: When light falls on an opaque object and a screen is placed behind the object, a shadow of the object is formed on the screen.