Q:

How does heat flow?

A:

Quick Answer

Heat flows from one object to another by conduction, convection or radiation, depending on the physical state of the medium through which it must flow. Heat always flows from a region of high temperature to a region of lower temperature. Without a temperature difference, there can be no heat flow.

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Full Answer

Solids transfer heat through conduction. The object to be heated must be in contact with the heat source. Molecules closest to the heat source are heated first. They then transfer the heat energy to the rest of the molecules in the object.

Fluids transfer heat through convection. Fluid molecules that are heated up are less dense because they have a higher kinetic energy and their increased movement causes them to spread apart. Therefore, in convection, hot fluids rise and cold fluids sink.

Radiation does not require a medium to transfer heat. Heat flows as an infrared wave, which is a type of electromagnetic wave. This is how heat flows from the sun to the earth.

For heat to flow, there must be a temperature difference between the two objects involved in heat transfer. Temperature indicates the average kinetic energy of the molecules of an object. If the molecules have a high kinetic energy and move around quickly, the object has a high temperature. These molecules have the ability to transfer their energy to molecules with lower kinetic energy (colder molecules). Thus, heat flows from an object of higher temperature to an object of lower temperature until both objects reach the same temperature.

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Related Questions

  • Q:

    How do you perform a simple heat-conduction experiment?

    A:

    Heat is transferred between two objects that are in contact with each other through conduction. When a pan containing uncooked meat is placed on a heated electric stove, heat transfers from the stove to the pan and the meat. The transfer can be detected as a rise in temperature in the meat as it cooks. This is one of the simplest demonstrations of heat conduction.

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  • Q:

    How does conduction work?

    A:

    Conduction works by transferring heat from one molecule to another through a substance. This occurs due to the readiness of the substance to allow molecules to move. A heated molecule moves and shakes rapidly, and some of its heat energy is passed to molecules around it.

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  • Q:

    When does conduction occur?

    A:

    Conduction occurs when two things that have different temperatures come into contact with each other. It occurs because the heat in the hotter object transfers into the material of the object that is not as hot.

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  • Q:

    What are some facts about conduction?

    A:

    Heat conduction depends on the electronic configuration, density, temperature and dimensions of the material. Conduction should not be confused with conductivity, which is dimension independent.

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