What is the difference between the transfer of heat bt radiation and the transfer of heat by conduction?

Answer 1

conduction is the transfer of heat in solids while convection is the heat transfer through fluids.conduction is only achieved by materials with electons in onvection currents are formed and hence the transfer of heat

Answer 2

Thermal energy that the Earth receives from the Sun travels through space via

electromagnetic radiation radiated from the Sun's photosphere who's effective

temperature is about 5 800 K. Thermal radiation is the one that lies between the wavelength of 0.1µ and 100µ of the electromagnetic radiation spectrum and includes visible light (0.38µ - 0.76µ). It can travel in vacuum, and of course, at the speed of light in vacuum (c ≈ 300 000 km/s).

The main mechanism of heat transfer within an opaque (not just to visible light but

to the rest of the thermal spectrum) solid is conduction. Thermal energy of a body is the sum of its molecules or atoms energies, like their translation energy energy (kinetic energy), rotation energy, vibration energy, electronic energy, ... In

the case of solids, the main component is molecular vibrations. When a solid body

is heated on some part of its surface, the molecules increase their vibration

energy, local temperature goes up. The more excited molecules (or atoms) pass

their energy to their neighboring less excited molecules (it could be said that by

'direct contact'). In that manner a cascade of energy is formed from the higher temperature region to the lower temperature region of the body. This heat transfer mechanism is called conduction. Conduction also occurs in liquids and gases. In gases this transfer occurs when molecules or atoms collide, that's why gases are not very good conductors of heat.

Heat transfer by convection can take place in liquids and gases. The transport of

heat is done by bulk motion of the fluid. There are two forms of convection:

Natural Convection and Forced Convection.

An example: Thermal radiation from the Sun first has to cross the Earth's

atmosphere before reaching its surface. In its way through the different

atmosphere layers part of the thermal radiation is reflected out, absorbed or

refracted. Absorbed thermal radiation heats some layers more some less of the

atmosphere. About 80% of the thermal radiation makes it to the Earth's surface,

and heats up the ground. In the interface ground-air air molecules that collide

with the solid ground get heated by 'conduction'. As air is heated it expands (its

density reduces) and buoyancy forces make warmed air to rise. This bulk motion

produced by the existence of a difference in temperature (higher temperature of the air close to the ground and lower temperature in the air above), that originates

a difference in density in the fluid is referred as 'natural convection'.

In the house on a warm day, when some body turns on an air ventilator to refresh

people, the motion of the air (convection) is now called 'forced convection', and

increases heat transfer by speeding up the replacement of the warm air film around our body by the cooler air further from the body.

Answer 3

Heat is a form of energy, conduction is a method of heat transfer