Peltier and Thomson effect [peltier and Thomson coefficient]

 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

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

$$units: JA^{-1}S^{-1}k^{-1}$$