[Physics Class Notes] on Seebeck Effect Pdf for Exam

The Seebeck effect is a major observation in the study of physics. It is widely used in the application of semiconductors and conductors, and thus, has a lot of practical applications for us in our daily lives. German physicist Thomas Jonahan Seebeck was the one who formulated this, when he noticed that a magnetic compass, when brought in close proximity of two semiconductors can undergo a variation. 

In short, the Seebeck effect explains the relationship between changes in temperature and semiconductors. 

What Is The Seebeck Effect?

In 1821, German physicist Thomas Seebeck had observed the properties of the thermoelectric effect. It was seen that a circuit that had two different metals developed an EMF when their junctures were maintained at different temperature levels. These non-similar metals form what is known as a thermocouple, and the current that passes through this circuit is known as thermoelectric current. 

The Seebeck effect explained the production of an electromotive force and the electric current in a loop of materials consisting of at least two dissimilar conductors maintained at two different temperatures, known as the thermocouples. It can be termed as the Seebeck effect thermocouple.

The Seebeck effect is a reversible process. If the hot and cold junctions are interchanged then the direction of the current will also change. Therefore, the thermoelectric effect is a reversible process. The magnitude and sign of thermo EMF depend on the materials of the two conductors and the temperature of the hot and cold junction.

Seebeck after discovering thermal properties of different pairs of metals arranged in series is called thermoelectric series. The thermoelectric effect is the conversion of temperature differences into electrical potential differences or vice versa using a thermocouple. 

The Seebeck effect is the best example of an electromotive force. Through the Seebeck effect, we can also calculate the measurable electric currents or voltages in the same way as electromotive forces.

The local current density can be calculated using the formula,

⇒ J = σ(-ΔV + [E_{emf}])

Where, ΔV – The potential difference developed

 [E_{emf}] – Electromotive force

σ – The local conductivity

The electromotive force created will explain the Seebeck effect and the equation of electromotive force in terms of the Seebeck coefficient is given by,

⇒  [E_{emf}] = -SΔT

Where, S – The Seebeck coefficient

ΔT – The temperature gradient

The Seebeck coefficient implies that a certain potential is induced in the circuit per change in temperature. It should be remembered that the Seebeck coefficients can change with temperature and they are dependent on the composition of the conductor. Usually it has been noticed that at room temperature, the Seebeck coefficient ranges between -100V/K to 1000V/K. 

What Are Some Applications Of the Seebeck Effect?

Due to the fact that this monitors the change in temperature with conductivity, it is very useful in a number of modern operations that require electricity and conductivity at differential temperatures. Some of the common applications of this property are:

• It can be useful in thermoelectric generators, which are used in industries and power plants to not let residual heat go waste and harness that into electricity. 

• In the automobile industry as well, the Seebeck effect can have many applications. It can be used to employ a thermoelectric generator which will lead to less fuel wastage. 

• It is also useful in thermocouples which can measure the potential difference between two semiconductors. Thermophiles are thermocouples arranged in series, and the Seebeck effect can be seen there as well.