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Does heat transfer require no direct contact between the warmer and cooler substances?
Wiki User
∙ 12y ago
Conductive heat transfer requires direct contact between warmer and cooler substances. However, two types of heat transfer require no direct contact between the warmer and cooler surfaces: convective heat transfer and radiative heat transfer.
In convective heat transfer, the warmer substance heats some intermediate substance - a gas like air or a liquid like water - which then moves either due to natural convection due to density differences or by forced convection driven by a pump or fan. The warmed fluid then imparts some of the energy it picked up from the warmer substance to heat up the cooler substance. In truth, this still relies on conduction to heat the fluid between the two and for the fluid to then heat the cooler substance, but there is clearly no direct contact between the heat source and the heat sink.
In radiative heat transfer, the energy is transferred between the two substances without any intermediate fluid. If it didn't work, the sun would be unable to warm the earth. The transfer occurs via electromagnetic radiation from the hotter substance to the cooler one. In truth, the cooler substance is also radiating back to the warmer one, but it receives much more energy from the warmer one than it is able to send back. The rate of radiation is proportional to the fourth power of the absolute temperature of the substance, so the net heat transfer between two substances is expressed by the formula:
q = ε σ (Th4 - Tc4) Ac
where q is rate of heat transferred, ε is the emissivity of the heat source, σ is the Stefan-Boltzmann constant, A is the surface area, and Th and Tc are the absolute temperature of the hot and cold substances respectively.
Wiki User
∙ 12y ago
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What is the method of transfer that does not require contact?
I assume you mean heat transfer. The answer is radiation.
Does conduction require direct contact?
convection requires a medium to travel. In space there is no air but, a vacuum. Therefore direct heat from the sun is radiation as it does not require a medium to travel.
Radiation require a heated liquid to transfer energy?
Radiation does not require a heated liquid to transfer energy.
What is the form of thermal transfer that does not require matter?
Energy transfer by radiation.
What is the opposite of convection?
Either of the two other means of energy transfer, radiation or conduction, could be the opposite -- but radiation moreso because it does not require molecular contact.
What is the method of transfer that does not require contact?
I assume you mean heat transfer. The answer is radiation.
Does conduction require direct contact?
convection requires a medium to travel. In space there is no air but, a vacuum. Therefore direct heat from the sun is radiation as it does not require a medium to travel.
Do objects require contact for the transfer of heat?
That depends, conduction does but radiation travels in waves so just goes through anything
Radiation require a heated liquid to transfer energy?
Radiation does not require a heated liquid to transfer energy.
What transfer of energy does require matter?
Radiation does not require matter.
What is the form of thermal transfer that does not require matter?
Energy transfer by radiation.
What is the opposite of convection?
Either of the two other means of energy transfer, radiation or conduction, could be the opposite -- but radiation moreso because it does not require molecular contact.
What is the energy transfer process that does not require the presence of molecules to transfer heat?
Radiation
Can you transfer from law school or med school to a completely different graduate school program?
That will depend on the school. Some will allow you to transfer between schools. Others might require you to simply reapply.
Transfer of energy that does NOT require matter is?
Radiation
Will a d transfer from university to university?
Most schools require a C or higher to transfer credit
Is vacuum a good conductor of heat?
Heat is the transfer of energy from one object or substance to another. There are three types of heat transfer - conduction, convection, and radiation. Conduction requires that the first object (or substance) be in direct physical contact with the second. A vacuum between the substances prevents this type of heat transfer, which is why double-paned windows are evacuated between the panes to reduce heat transfer to the outside. Convection occurs when atoms or molecules move in fluids (gases or liquids), and carry the kinetic energy of molecular motion with them. Since a vacuum doesn't contain any atoms or molecules, convection will not occur in a vacuum. Technically, a vacuum would allow atoms and molecules to convect through it, but then it wouldn't be a full vacuum. Radiation is energy transfer by electromagnetic waves (light). Light does not require a medium to propagate and will travel perfectly well through a vacuum, which is how the energy of the Sun is transferred to the Earth. So heat can be transferred through a vacuum by radiation.
