BAHRIA COLLEGE ISLAMABAD GENERAL SCIENCE new lower secondary

BAHRIA COLLEGE ISLAMABAD GENERAL SCIENCE (new lower secondary science II) CLASS VIII MISS IQRA AKRAM

FIRST TERM SYLLABUS Unit No. 1 ATOM AND MOLECULES PG NO 03 Unit No. 2 CHANGES IN MATTER PG NO 06 Unit No. 5 CRYSTALS PG NO 09 Unit No. 10 TRANSPORT IN LIVING ORGANISM PG NO 12 Unit No. 13 LIGHT PG NO 136

Unit #13 = light pg#136 Qno 1: what are characteristics of light? Light is form of useful energy that supports life. It can be detected by our eyes and can be transferred from one place to another. Light does not need a medium to travel in. It can travel in a vacuum. The speed of light in a vacuum is 300 million meters per second (3 x 10^8 ms-1). Light travel in a straight line. The path along which light travels is called a ray.

Sources of light Qno 2: what are sources of light? Ans: there are two different sources of light. 1. Natural sources of light = sun 2. Artificial sources of light = candle, bulb, tube light

Some other characteristics of light: Qno 3: define the following term: 1. Luminous 2. non- luminous objects 3. opaque 4. transparent 5. translucent Luminous object: object that give out light of their own. E. g. sun Non- luminous object: object that don't give out light of their own. E. g. moon Opaque object : material that do not allow light to pass through it. E. g. wood, metal Transparent object: materials allow almost all light to pass through them. E. g. glass, water and air. Translucent object: materials allow some light to pass through them. Materials look blur. e. g. frosted glass,

Topic # shadow pg#139

How shadow is formed? Shadows are formed when light is blocked by an opaque object. Light cannot bend round the opaque object because it travels in a straight line. Thus, a region of darkness behind the object is called shadow.

Parts of shadow: The region of complete shadow is called the umbra and the region of diffuse shadow is called the penumbra. These shadows are formed on the Earth during a solar eclipse and From the umbra we see a total eclipse while from the penumbra only a partial eclipse is visible. If you look at the picture of the baby and the umbrella, you will notice that both of them leave a very dark shadow. The umbrella is there to help you remember that the dark part of the shadow is called the umbra. See how umbra and umbrella sound alike? Also, many umbrellas are black, so that similarity in words can help you remember that the umbra is black. Some shadows have lighter areas, too, and those are called penumbras.

Solar and lunar eclipse

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