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Heat and Light Summary - Contenido educativo
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Good morning everyone! Today I'm going to review with you this unit about heat and light.
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Heat is the transmission of thermal energy.
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As you saw in your experiment, heat makes particles move faster.
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This movement makes different things happen.
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For example, heat is transmitted in three different ways, if you remember, it always
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transmits from a hot object to a colder object.
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And the three ways in which the heat transmits are conduction, do you remember, like when
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you're cooking something and it's in touch with something hot, it becomes hot.
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So for conduction, the two objects have to be in contact.
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Then we have convection, which happens in liquids and gases.
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This drawing is to remind you about boiling water.
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When you see boiling water, it's because the water next to the source of heat is hotter, it moves faster, it goes up, and then it cools down and goes down.
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So making this circular movement. Then we have radiation. Radiation doesn't need anything to be transmitted. It can be transmitted in space, where we don't have any matter. Radiation is the heat we receive from the sun travels through radiation.
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Remember that some materials are the conductors, materials that transmit heat easily, like for example metal, and then we have the insulators, materials that don't transmit heat easily, for example wood or some plastics, what in Spanish we call the aislantes, insulators, the ones that we use for the oven, for touching things that are hot.
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Okay, then, as particles move faster, this causes changes in materials, okay, the effects of heat, which are of three different ways, okay?
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We have the changes of state, these are physical changes, you know them from other courses, they are physical because they can be reversed, okay?
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If we have ice and we heat it, it melts and we have liquid, we heat it, it evaporates and we have gas.
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But if we cool down the gas it becomes liquid again, if we cool down the liquid it becomes
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solid again, so it's reversible.
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Then we have the expansion, some materials can be expanded with heat, like for example
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the example of the trail, of the railway.
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And then we have the chemical changes, chemical changes can't be reversed, we have the examples
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of when you're making a cake. You do the daff, then you heat it in the oven, and you have
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your cake. But it cannot be reversed. You cannot put the cake in the freezer, for example,
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and then have the daff again, with the flour and the sugar and the eggs.
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Okay, the same with, for example, paper. If you burn paper, it becomes ashes and smoke.
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If you put the ashes and smoke back in the fridge or somewhere you cool it down, it doesn't
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become paper again. So these changes are chemical, they can't be reversed.
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These are the important things about heat. Let's review the things about
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light. Light is a form of radiant energy. Light travels very
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fast, is the element that we know that travels the fastest in the universe, and
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it travels in the form of electromagnetic waves. So it can travel
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also in the space. It doesn't need any material to be transmitted. It travels in
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straight lines and thus it hits objects. And thanks to the light hitting
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objects we can see the objects. As we see the objects there are three
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different types of objects according to how light hits them. We have the opaque
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objects or materials these are the ones that block the light and project a
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shadow okay light don't passes through them don't pass through them then we
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have the translucent materials which let a little light pass through and then we
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have the transparent materials which let all the light pass through okay this is
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Then we have the basic laws of light, which are reflection.
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Light, when it hits some special, very smooth surfaces, can be reflected, can change direction.
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Light can also change a little the direction when it travels through a different element,
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for example, from the air to a liquid.
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And then we have the white light, which contains all the colours we can see, the spectrum.
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When the white light passes through a person, we can see the different rainbow, the colors
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of the rainbow spectrum, all the colors that we can see.
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There are more colors, but we cannot see them.
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There are the ultraviolet and the infrared, there are different ways that we cannot see.
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So these are the important things about heat and light.
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See you later!
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- Idioma/s:
- Subido por:
- Isabel María M.
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 112
- Fecha:
- 26 de mayo de 2020 - 9:37
- Visibilidad:
- Público
- Centro:
- CP INF-PRI CARMEN IGLESIAS
- Duración:
- 05′ 47″
- Relación de aspecto:
- 1.78:1
- Resolución:
- 1364x768 píxeles
- Tamaño:
- 12.20 MBytes
