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Hi everyone. For your next natural science class on Thursday, you need to watch this presentation

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about light. What are we going to learn about in this presentation? We're going to learn what is

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light energy, what are the two types of light sources, and how does light travel? Remember we

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spoke about sound and we said that sound is a type of energy? Well, light is a form of energy as well.

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Light is a form of energy that allows us to see the things around us.

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All light either comes from natural light sources or from artificial light sources.

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What are natural light sources?

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These light sources are found in nature.

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And let's have a look at a few examples.

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Lightning, the sun, a meteor, stars in the sky, a volcano, and even this jellyfish.

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Some animals produce their own light.

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We call these animals bioluminescent animals, and most of them live in the ocean.

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We said that natural light sources are found in nature.

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So, where do artificial light sources come from?

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These light sources are created by people.

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The light energy is transformed from another type of energy, like chemical energy or electrical energy.

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We cannot find these sources of light in nature.

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For example, a candle is an artificial light source, and a flashlight and a lamp as well.

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A computer screen, sparklers, and fireworks are examples of artificial light sources.

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With a computer screen, electrical energy is transformed into light energy.

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With the sparklers and fireworks, chemical energy is transformed into light energy.

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Do you know how light travels?

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First of all, light travels in straight lines.

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When you shine a torch at night, you can see that light travels in a straight path.

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Another way of seeing how light travels is when you go in a car at night.

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When you're in a car at night, you can see that the headlights shine on things in front of the car,

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but they cannot light things up that are on the side of the car.

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light travels extremely fast much much faster than sound it travels at nearly 300 000 kilometers

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per second and we call that the speed of light so i hope that you found today's class interesting

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and just to make sure that you understand make sure that you can answer these questions the

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first question what is light the second question what are the different sources of light and try

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to remember examples of each one and the third question how does light travel ah and by the way

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an extra question for the next class is the moon a natural light source why why not