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Methods of Energy Transfer

Methods of Energy Transfer. The transfer of heat energy from a hot object can occur in three ways: C onduction is the transfer of energy as heat through a material. Convection is the movement of matter due to differences in density that are caused by temperature variations.

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Methods of Energy Transfer

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  1. Methods of Energy Transfer The transfer of heat energyfrom a hot object can occur in three ways: • Conductionis the transfer of energy as heat through a material. • Convectionis the movement of matter due to differences in density that are caused by temperature variations. • Radiation is the energy that is transferred as electromagnetic waves, such as visible light and infrared waves.

  2. Methods of Energy Transfer, continued • Conduction • Conduction involves objects indirect contact. • Conduction takes place when two objects that are in contact are atunequal temperatures.

  3. Methods of Energy Transfer, continued • Convection • Convection results from the movement of warm fluids. • During convection, energy is carried away by a heated fluid that expands and rises above cooler, denser fluids. • Aconvection currentis the vertical movement of air currents due to temperature variations.

  4. Methods of Energy Transfer, continued • Radiation • Radiation is energy transferred as heat in the form ofelectromagnetic waves. • Unlike conduction and convection, radiation does not involve the movement of matter. • Radiation is therefore the only method of energy transfer that can take place in a vacuum. • Much of the energy we receive from the sun is transferred by radiation.

  5. Conductors and Insulators Any material through which energy can be easily transferred as heat is called aconductor. Most metals are good conductors.

  6. Conductors and Insulators Poor conductors are calledinsulators. • Gases are extremely poor conductors. • Liquids are also poor conductors. • Some solids, such as rubber and wood, are good insulators.

  7. Conductivity A measure of the ability of a material to transfer heat

  8. Specific Heat • Specific heatdescribeshow much energyis required toraise an object’s temperature. • Specific heatis defined as the quantity of heat required to raise a unit mass of homogenous material 1 K or 1°C in a specified way given constant pressure and volume. Specific Heat Equation energy = (specific heat)  (mass)  (temperature change) energy = cmDt

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