This PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections will help you in revision during exams.
PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections
→ Light is a form of energy that enables us to see the things around us.
→ A source of light can be either natural or artificial as for example Sun, Moon, Stars CFL, Candle, and LED.
→ Light ordinarily travels along a straight path.
→ Opaque objects do not allow light to pass through them and the objects lying on the other side of it cannot be seen.
→ Transparent objects allow light to pass through them and we can see through these objects clearly.
→ Translucent objects allow light to pass through them partially and the objects lying on another side of these objects are not seen clearly.
→ Shadows are formed when an opaque object comes in the path of light.
→ A pinhole camera can be made with simple materials and can be used to obtain the image of the Sun and other bright (luminous) objects. This image is inverted and small in size.
→ Reflection from the mirror gives us clear images.
→ Luminous Object: Such objects have light of their own and give out light.
→ Non-Luminous Object: Such object which has no light of its own and becomes luminous from light emitted by other luminous objects.
→ Light: It is a form of energy that enables us to see the surrounding objects but light itself is not seen.
→ Source of light: Such luminous bodies which have the light of their own and which emit light as for example candle CFL etc. The source light may either be a Natural or Artificial source.
→ Transparent objects: Such objects through which light can pass and on the other side of which we can see clearly are called transparent objects. Examples are Air, water, glass, etc.
→ Opaque objects: Those objects which do not allow light to pass through them and the objects on the other side of which cannot be seen are called opaque objects. Examples are Cardboard sheets, wood, metal, and rubber, etc.
→ Translucent objects: Those objects through which light can pass but partially and the objects lying on the other side of which are not seen clearly are called translucent objects. Examples are Tissue paper, thin cloth, oiled paper, etc.
→ Shadow: When an opaque object is placed in the path of the light rays coming from a source of light then light cannot pass through and a black region is formed on the other side of the opaque body. This black region where no light is received is called the shadow. The size of the shadow can be small or large.
→ Sundial: It is an instrument that shows time with the help of shadows formed by sunlight.
→ Solar Eclipse: When the moon while revolving around the earth comes in such a situation that the moon is in between the earth and the sun and all the three are in a straight line then the shadow of the sun is formed on the earth, a solar eclipse is said to occur.
→ Lunar Eclipse: When the earth comes in between the sun and moon and all the three are in a straight line and the shadow of the moon is formed on the earth; then the lunar eclipse is said to occur.
→ Pinhole camera: It is an instrument in which the inverted and small-sized image of a stationary object such as a building or tree is formed. It is constructed on the principle of propagation of light in a straight line.
→ Mirror: Any smooth and polished surface which changes the path of light rays falling on it, is called a mirror.
→ Reflection of light: When light falls on a mirror and light falling on it is sent back into the same medium in a particular direction, then this phenomenon of change of direction of the path of light is called reflection of light. Reflection of light is of two types:
- Regular reflection
- Irregular reflection
→ Regular reflection: When light falls on a smooth plane mirror or a polished surface then a reflection of light takes place in a regular manner. This reflection of light is called regular reflection.
→ Irregular reflection: When light falls on any rough or uneven surface than light rays after reflection gets scattered. This reflection of light is called irregular reflection. We can see the various objects around us due to this reflection.