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Thermal Radiation

Thermal Radiation. Done By: Nujood Al- hashar Abrar Al- haddabi Kawthar al- lawati Maria al- wahaibi. Thermal Radiation.

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Thermal Radiation

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  1. Thermal Radiation Done By: Nujood Al-hashar AbrarAl-haddabi Kawthar al-lawati Maria al-wahaibi

  2. Thermal Radiation • The sun’s energy travels to us in a vacuum. they can travel through a vacuum (empty space). They heat up things that absorb them, so are often called thermal radiation.

  3. Thermal Radiation • All objects give out some thermal radiation. • The higher their surface temperature and the greater their surface area, the more energy they radiate per second. • Warm objects radiate infrared.

  4. Thermal radiation is mainly infrared waves, but very hot objects also give out light waves.

  5. Emitters and absorbers • Some surfaces are better at emitting (sending out) thermal radiation than others. For example a black saucepan cools down more quickly than a similar white one because it emits energy at a faster rate.

  6. Emitters and absorbers Dull, black surfaces are better absorbers than shiny/white surfaces.

  7. Emitters and absorbers Shiny/white surfaces are better reflectors than dull black surfaces.

  8. This chart shows how some surfaces compare as emitters, reflectors, and absorbers of thermal radiation.

  9. Emitters and absorbers Comparing emitters Comparing absorbers The metal plates are placed at the same distance from a radiant heater. To find out which surface absorbs thermal radiation most rapidly, the rises in temperature are compared. • The metal cube is filled with boiling water which heats the surfaces to the same temperature. • The thermal radiation detector is placed in turn at the same distance from each surface and the meter readings are compared.

  10. Emitters and absorbers Comparing emitters Comparing absorbers

  11. Solar panel • A solar panel uses the sun’s thermal energy to worm up water for houses. • The blackened layer absorbs the radiant energy and warms up water flowing through the pipes.

  12. Vacuum flask • A vacuum flask can keep drinks hot or cold. • It has these features for reducing the rate at which thermal energy flows out or in: • An insulated stopper to reduce conduction and convection. • A double-walled container with a gap between the walls. Air has been removed from the gap to reduce conduction and convection. • Walls with silvery surfaces to reduce thermal radiation.

  13. Refrences Book Complete Physics for IGCSE By Stephen Pople

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