Nature of Light


 
 
Concept Explanation
 

Nature of Light

Light:  Light is a form of energy which creates the sensation of vision or we can say it helps us to see the things around us

  • We are able to see an object only when the light coming from the object enters our eyes. We cannot see the objects in a dark room. We need a light source to make an object visible . When the light falls on an object it is reflected back. This reflected light enters our eyes and we can see that object.
  • It is essential for life on earth. The process of photosynthesis requires light. Also, during photosynthesis oxygen is given off. We breathe in this oxygen.
  • When we burn wood for cooking or for warming ourselves, we actually utilize the energy of sunlight that is locked up in plants. Infact the energy of all fossil fuels, such as petroleum, coal and natural gas has also been derived from the light energy.
  • How fast does light travel?

  • ·   Galileo once tried to measure the speed of light by trying to measure the time it takes to travel from one hill to another, but he could not. This is because light travels very fast- its speed is about 3, 00,000 km per second in air.
  • ·   No object can travel as fast as light. The distance from the sun to the earth is 1485 lakh kilometers. Light travels from the sun to the earth in 81/4 minutes. That means you see the sun rising minutes after it has already risen. It takes light several years to travel from the stars to the earth.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    To see various objects we need _____________________.

    Right Option : C
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    Explanation
    Question : 2

    Light is essential for life on earth because _________________.

    Right Option : C
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    Explanation
    Question : 3

    Which of the following are correct ?

    (a) The reflected light from the object enters our eyes and we can see that object.

    (b)  The energy of all fossil fuels, such as petroleum, coal and natural gas has also been derived from the light energy.

    (c) Light travels very fast- its speed is about 5, 000,00 km per second in air.

    Right Option : A
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    Explanation
     
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