What isThermoelectric effact

 Thermoelectriceffect : the phenomena of production of current in thermocouple due to variation of heat is called thermoelectric effect .

It is classified into three different effects

• Seebeck effect
• Peltier effect
• Thomson effect

Seebeck effect: the phenomena of production of current in thermocouple due to temperature difference between two junction of thermocouple called seebeck effect.

      Thermocouple

produced EMF depend upon separation between metals , nature of metal and temperature difference of junction.

Cause of seebeck effect:

• Potential difference
• Different electron density
• Temperature difference create net potential difference which creating thermocouple EMF

\[Qn= \frac{ Q_{i}+ Q_{c}}{2}\]

Peltier effect : the phenomena of evaluation observation of heat at junction of thermocouple when current is made to pass through it is called peltier effect.

• Heat is evolved or absorbed

heat or cooling of function is determined by direction of current

Current flow through fe to Cu . heat will released  Cu to Fe. it will absorbed at cold junction. This effect is reverse of seebuck effective.

Cause of peltier effectcurrent

• Electron density increase at junction
• Electric field due to applied voltage

Heat absorb or release is directly proportional to current and temperature.

i.e.     \[Q\ \alpha\ IT \rightarrow or \ Q =\pi IT\]

\[\Rightarrow \ \pi=\frac{Q}{It} \ or \frac{Q}{\frac{q}{t}t}\]

Cancling t

 \[ units : JC^{-1}\]

Thomson effect: phenomena of evaluation or observation of heat along the length of an equally weighted conductor is called Thomson effect.

Cause of Thomson effect

• electron density gradient developed along length of conductor due to unequal heating of conductor.

Thomson coefficient: heat absorbed or evolved a long length of conductor/unit current/unit time, when and of conductor are maintained at unit temperature difference

\[Q\ \alpha \ I \rightarrow \ Q \ \alpha \ Itdt\Rightarrow \ \ Q=\partial Itdt \\\\ \partial=\frac{Q}{Itdt}=\frac{Q}{\frac{q}{t}tdt}=\frac{Q}{qdt}\]

\[ units: JA^{-1}S^{-1}k^{-1}\]