We also get light from objects like bulb, torch, candle, lantern, oil lamp and table lamp.
Luminous Objects: Objects that give light.
Non-luminous Objects: Objects like table, chair etc that do not give light.
Transparent Materials: Materials like glass, air etc that allow light to completely pass through them.
Translucent Materials: Materials like frosted glass and butter paper that allow light to pass through them partially.
Opaque Objects: Objects like wood, bricks etc that do not allow light to pass through them.
Rays: The straight lines along which light travels.
Shadow: A shadow is formed when an opaque object blocks the path of light.
Our Earth moves around the Sun. And the moon revolves around the Earth.
Earth and moon do not have light of their own. They receive light from the Sun and reflect the light that falls on them.
Solar Eclipse: On some new moon days the moon comes in between the Sun and the Earth and blocks the sunlight from falling on Earth. A shadow of the moon is formed on the Earth and people in this shadow region cannot see the Sun either totally or partially, for sometime. Such a phenomenon is called a Solar Eclipse.
Lunar Eclipse: On some full moon days the Earth comes in between the Sun an the Moon and blocks the sunlight from falling on the Moon. A shadow of Earth is formed on the Moon and thus people cannot see moon (partially or totally) for sometime. Such a phenomenon is called a Lunar Eclipse.
Sound: We hear different sounds around us. We produce sound when we speak or laugh.
Pleasant Sounds: Soft sounds that make us happy.
Noise: Unpleasant sounds that irritate us and make us sick. Unpleasant sounds cause noise pollution.
We should avoid noise pollution by speaking softly, playing music / TV in low volumes etc.
We do different types of works in our daily life. For doing work we either push or pull something by applying force on it.
What is force? The push or pull applied on an object is called force.
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