Difference Between Convection and Radiation
- For convection to occur, a medium with movable particles must be present around the heated body. Radiation does not require any medium.
- The heat transfer from radiation is faster than the heat transfer from convection.
- Convection always carries the heat away from the gravity, whereas radiation is emitted in every direction.
What is the temperature at the radiation zone of the Sun?
The temperature at the radiation zone ranges from 2 to 7 million degrees Celsius. Continuing on with our journey, as a photon, our last stop must be the convection zone. At the convection zone this is the outermost layer of the Sun where convection currents occur.
What is the convective zone?
Convective Zone This region is over the radiative zone. As the name says, the transport of the energy is made by convection, so, the heat is transported in a non homogeneous way by the fluid. This zone has a thickness of 300000 Km. The energy is radiated through the plasma.
What is the difference between convection and radiation?
The main difference between convection and radiation is that convection is a mechanism of heat transfer which involves a mass flow of material. Radiation, on the other hand, is a transfer of heat using electromagnetic energy.
What is the temperature of the convection zone of the Sun?
At the convection zone this is the outermost layer of the Sun where convection currents occur. The convection currents take us, the photon, to our final destination: which is the outer surface of the Sun. The temperature of this zone is approximately 2 million degrees Celsius.
Why is convection important?
Convection is also an important factor in plate tectonics. The inner parts of the Earth’s mantle is hotter than the outer part, and this causes convection cells to be set up in the mantle. The mantle is solid, and the movement of material within the mantle is quite slow, about 20 mm per year. Convection in the Earth’s Mantle.
What is the difference between convection and radiation?
The main difference between convection and radiation is that convection is a mechanism of heat transfer which involves a mass flow of material. Radiation, on the other hand, is a transfer of heat using electromagnetic energy. Consequently, radiation can transfer heat through a vacuum.
What is the emissivity of a surface?
The quantity is called emissivity. It takes a value between 0 and 1. is higher for darker objects with darker surfaces, which emit and absorb radiation well. Shiny surfaces absorb and emit much less radiation and they have emissivities closer to 0. An ideal surface that is both a perfect absorber and an emitter of radiation has an emissivity of 1 and is called a blackbody.
What is the transfer of heat through electromagnetic radiation?
What is Radiation. Radiation describes the transfer of heat via electromagnetic radiation. Due to kinetic energy, molecules that make up objects are always in motion. This causes charges in those molecules to move, which results in the creation of electromagnetic waves.
What is the primary wavelength radiated by a blackbody?
At room temperature, the primary wavelength radiated by bodies is in the infra-red range. The graph below shows the energy density of a given wavelength radiated by a blackbody at several different temperatures.
What is the purpose of thermography?
Thermograms make use of thermal radiation emitted by the body to screen diseases and infra-red cameras are used to “see” in the dark. Radiation from distant stars is also used to measure the distance between the Earth and the stars.
What is convection in science?
What is Convection. Convection is the mechanism of heat transfer in materials through mass flow of the material. In order to conduct heat, parts of the material itself moves — i.e. there is a transfer of mass within the material. Typically, convection occurs in fluids. However, effects of convection can be seen sometimes in solids, ...
What is the difference between convection and radiation?
Convection is the method of transferring heat using moving particles. Radiation does not require particles or a medium to transfer energy. Both of these processes are very important in numerous fields.
What is electromagnetic radiation?
Electromagnetic radiation or commonly known as radiation or EM radiation is a method of heat transfer. Electromagnetic radiation was first proposed by James Clerk Maxwell. This was later confirmed by Heinrich Hertz who successfully produced the first EM wave. Maxwell derived the wave form for electric and magnetic waves and successfully predicted the speed of these waves. Since this wave velocity was equal to the experimental value of the speed of light, Maxwell also proposed that light was, in fact, a form of EM waves. Electromagnetic waves have both an electric field and a magnetic field oscillating perpendicular to each other and perpendicular to the direction of wave propagation. All electromagnetic waves have the same velocity in vacuum. The frequency of the electromagnetic wave decides the energy stored in it. Later it was shown using quantum mechanics that these waves are, in fact, packets of waves. The energy of this packet depends on the frequency of the wave. This opened the field of wave – particle duality of matter. Now it can be seen that electromagnetic radiation can be considered as waves and particles. An object, which is placed in any temperature above the absolute zero, will emit EM waves of every wavelength. The energy, which the maximum number of photons emitted, depends on the temperature of the body.
How does convection work?
Unlike conduction, convection cannot take place in solids. Convection is the process of transferring energy through direct matter transfer. In liquids and gasses, when heated from the bottom, the bottom layer of the fluid will be heated first. The heated air layer then expands; being less dense than the cool air, the hot air layer rise in the form of convection current. Then the next fluid layer is experiencing the same phenomena. Meanwhile, the first hot air layer is now cooled down, and it will come down. This effect creates a conduction loop, continuously releasing the heat taken from the lower layers to the upper layers. This is a very important pattern in weather systems. The heat from the surface of the earth is released to the upper atmosphere in this mechanism.
When a liquid is heated from the bottom, what happens to the bottom?
In liquids and gasses, when heated from the bottom, the bottom layer of the fluid will be heated first . The heated air layer then expands; being less dense than the cool air, the hot air layer rise in the form of convection current. Then the next fluid layer is experiencing the same phenomena.
What happens to an object when it is placed in a temperature above the absolute zero?
An object, which is placed in any temperature above the absolute zero, will emit EM waves of every wavelength. The energy, which the maximum number of photons emitted, depends on the temperature of the body.
Does radiation require a medium?
Radiation does not require any medium. • The heat transfer from radiation is faster than the heat transfer from convection. • Convection always carries the heat away from the gravity, whereas radiation is emitted in every direction.
Do all electromagnetic waves have the same velocity?
All electromagnetic waves have the same velocity in vacuum. The frequency of the electromagnetic wave decides the energy stored in it. Later it was shown using quantum mechanics that these waves are, in fact, packets of waves. The energy of this packet depends on the frequency of the wave. This opened the field of wave – particle duality of matter.
Convective Zone
This region is over the radiative zone. As the name says, the transport of the energy is made by convection, so, the heat is transported in a non homogeneous way by the fluid. Ascendant currents are formed from the hot zone to the upper zone, and, at the same time, descendant movements of materials are produced from the external cool areas.
Radiative Zone
This zone has a thickness of 300000 Km. The energy is radiated through the plasma. That energy is released as photons "Υ" and that radiation is absorbed and re-emitted thousand times before leaving the upper layers converted into Y, X & ultraviolet rays, visible light and infra-red (heat).