1. Light -
ü The form of energy that enables us to see is called as light.
ü The objects which emit their own light are called as luminous. For example - sun, it emits radiation(energy).
ü Some objects do not emit their own light, but they shine as they reflect the light. For example - moon, it reflect the light (energy) of sun. Such objects are called non luminous.
2. Transparent, Translucent And Opaque -
ü The substances through which we can see clearly are called as transparent. Example window glass of a car.
ü The substances through which we can not see clearly are called translucent. Example rough glass of washroom window.
ü The substances through which we can not see through at all are called as opaque. Example a brick wall.
3. Shadows -
ü A shadow is formed when an opaque object comes in path of the light.
ü A shadow needs a surface where it is formed, such surface is called screen. for example- walls of a room.
ü Shadows give us an outline about the shapes of different objects.
4. Pinhole Camera -
ü A pinhole camera is a 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.
ü The light from outside enters through the small hole and forms an image on the screen that is inverted (upside - down).
5. Mirror -
ü A mirror is a surface that consist of a glass that reflects light incident on it to form clear and erect images.
ü A mirror works on the principle of reflection. When light is incident on a surface, it gets reflected or it bounces back. This phenomena is called reflection.
ü Any surface that is well polished or shiny acts like a mirror.
ü Images have colour, unlike shadows. They are formed due to the converging rays of light that comes after reflecting from objects.
ü A real image is formed by actual convergence of light rays. Real images always form on a screen.
ü A virtual image is the apparent convergence of diverging light rays. Virtual images cannot be obtained on a screen.
1. Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
Ans. - Opaque objects make shadows.
2. Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:
Air, water, a piece of rock, a sheet of aluminum, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, the moon.
3. Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?
Ans. - Yes
4. In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?
Ans. - No, in a dark room, a mirror reflection of the image will not be formed as the light will not fall on the mirror and thus no reflection will occur.
Junior Science Topic - Light, Shadow And Reflection. Chapter notes, video lectures, power point presentation and NCERT exercise solution. (Class 6, CBSE syllabus, chapter 11)
By - EduPorm India - The Educational Platform
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