How is convecton different from conduction?

Answer 1

Conduction warms the atmosphere as fast-moving molecules come into contact with lower-energy molecules until all molecules are moving at about the same rate. As the atmosphere warms, molecules move apart. As the heated air flows, heat is transferred by convection from warm, low-pressure air to cooler, high-pressure air.

Answer 2

Well it differs in this way. Conduction is when heat is applied to an object and causes mainly the point of contact to be heated. For example lighting a match under a metal rod. It will mainly heat the point of contact, eventually heating the rest of the rod. Additionally, conduction can be referred to when talking about electricity and whether a material can conduct or not.

Convection is different as it disperses heat evenly through a liquid. For example, boiling water. A single point of the water is heated, then it rises, allowing colder water from the top to fall, heat, rise and creates a current, evenly heating the water. The same example can be used when referring to preheating an oven.

Hopefully this helps.

Convection involves the actual movement of fluid materiel, either liquid or gas, usually in a gravitational field where the difference in temperature causes difference in density which in turn causes fluid motion.

Conduction can and does occur concurrently with convection, but does not involve the macroscopic movement of materiel. Conduction can occur in gasses or liquids, but also in solids. Conduction occurs when the thermal vibrations of hotter mater are transferred to cooler matter.

There is a third method of heat transfer, Radiation. Radiation can occur in all three phases of matter, but can also transfer heat across a vacuum. Usually thermal radiation is in electromagnetic wavelengths too long to be visible, but in some situations like an incandescent bulb or the sun, it can be seen.

Answer 3

Conduction is the transfer of heat between substances by direct contact without motion of the intervening substance.

Convection is the transfer of heat through bulk motion of intervening fluid (gases and liquids) between points with different temperatures.

Ex

Conduction- putting your foot on a cold concrete floor

Convection- a cold draft coming off the ceiling

Convection can be natural, caused by temperature induced density differences in the fluid, or forced, caused by an external process like a fan or the wind.

Answer 4

First of all the letter used ( J ) is a letter to mean current density so this is why you see it in both types of currents.

Convenction Current Density is a relation of the current density to the speed of volumetric charge density in a certain point. Simply put is the amount of current passing in a time t through a surface S. This surface is always perpendicular to the current flow. For example: If you wanted to increase the traffic in a tunnel, you will do it by increasing the speed of the cars or by increasing the number of cars (if this could be done) putting one on top of another. (ie increasing the density per cubic inch)

Conduction Current Density refers to the amount of current (charges) flowing on the surface of a conductor (conduction band) in a time t. This surface is always parallel to the current flow. This phenomenon is what gives a material its conductive nature and this happens because the energy gap between the valency band of the material and its conduction band is narrow. A wide energy gap causes the electrons not to have enough energy to jump to the conduction band and makes this material an isolator.

Answer 5

Convection is the actual movement of the molecules from one object to another. Typically, we think of heat moving through air. Consider a toaster, also known as a convection oven...the air inside of the toaster is heated and the food inside the toaster is heated through convection.

Conduction is the transfer of molecules directly from object to object. For example, think about if you touch a hot stove. Your hand on the hot stove will indeed burn you due to conduction of heat (do not however put your hand on a hot stove).

Hope this helps!

Answer 6

In conduction, heat moves from one body to another body it is in contact with by the collision of molecules of the hotter body imparting some of their energy to the molecules of the cooler body.

In convection, the hotter body imparts some of its energy to an intervening medium which then moves to the cooler body and imparts some of the energy it picked up from the hotter body. In cases of natural convection, the movement is due to density differences. In the case of forced convection, the movement is due to a fan or pump or some other mechanism causing the flow.