Question

Define conduction. What are the necessary conditions for the conduction of heat?​

Answer 1

Answer:

✯What is Conduction?

The process in which heat flows from objects with higher temperature to objects with lower temperature.

✯Conduction Equation

The coefficient of thermal conductivity shows that a metal body conducts heat better when it comes to conduction. The rate of conduction can be calculated by the following equation:

$\boxed{Q =  \frac{[K.A.(T _{ hot}−T _{cold} )]}{d}}$

Where,

• Q is the transfer of heat per unit time
• K is the thermal conductivity of the body
• A is the area of heat transfer
• Thot is the temperature of the hot region
• Tcold is the temperature of the cold region
• d is the thickness of the body

✯Conduction Examples

• Ironing of clothes is an example of conduction where the heat is conducted from the iron to the clothes.

• Heat is transferred from hands to ice cube resulting in the melting of an ice cube when held in hands.

• Heat conduction through the sand at the beaches. This can be experienced during summers. Sand is a good conductor of heat.

Explanation:

◉LET'S EXPLORE MORE

✯What is Convection?

The movement of fluid molecules from higher temperature regions to lower temperature regions.

✯Convection Equation

As the temperature of the liquid increases, the liquid’s volume also has to increase by the same factor and this effect is known as displacement. The equation to calculate the rate of convection is as follows:

$\boxed{Q = h _{c}()  ∙ A ∙ (T _{s} – T _{f} )}$

Where,

• Q is the heat transferred per unit time
• Hc is the coefficient of convective heat transfer
• A is the area of heat transfer
• Ts is the surface temperature
• Tf is the fluid temperature

✯Convection Examples

• Boiling of water, that is molecules that are denser move at the bottom while the molecules which are less dense move upwards resulting in the circular motion of the molecules so that water gets heated.

• Warm water around the equator moves towards the poles while cooler water at the poles moves towards the equator.

• Blood circulation in warm-blooded animals takes place with the help of convection, thereby regulating the body temperature.

✯What is Radiation?

Thermal radiation is generated by the emission of electromagnetic waves. These waves carry away the energy from the emitting body. Radiation takes place through a vacuum or transparent medium which can be either solid or liquid. Thermal radiation is the result of the random motion of molecules in the matter. The movement of charged electrons and protons is responsible for the emission of electromagnetic radiation.

✯Radiation Equation

As temperature rises, the wavelengths in the spectra of the radiation emitted decreases and shorter wavelengths radiations are emitted. Thermal radiation can be calculated by Stefan-Boltzmann law:

$\boxed{P = e ∙ σ ∙ A· (Tr – Tc) {}^{4} }$

Where,

• P is the net power of radiation
• A is the area of radiation
• Tr is the radiator temperature
• Tc is the surrounding temperature
• e is emissivity and σ is Stefan’s constant

✯Radiation Example

• Microwave radiation emitted in the oven is an example of radiation.

• UV rays coming from the sun is an example of radiation.

• The release of alpha particles during the decaying of Uranium-238 into Thorium-234 is an example of radiation.