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Seebeck Effect

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What is Seebeck Effect?

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The German physicist Thomas Johanan Seebeck first observed the Seebeck effect when a magnetic compass was brought near a loop connecting two conductors, he noticed a variation in the compass. The Seebeck effect mainly focuses on thermoelectric effects. The Seebeck effect is also known as the thermoelectric effect.

While studying the thermoelectric effect in detail, one of the important concepts we come across is the Seebeck effect. The Seebeck effect explains the presence of potential difference when a semiconductor or the conductors are subjected to the temperature difference. The Seebeck effect is used to measure the temperature with accuracy and generates the electric current for some applications.

Understanding Seebeck Effect

• Thomas Johann Seebeck in the year 1821 gave a detailed description of the thermoelectric effect or the Seebeck effect. He discovered that in a circuit consisting of two dissimilar metals (like iron and copper) an EMF is developed when the junctions are maintained at different temperatures.

• Two dissimilar metals connected to form a junction are known as a thermocouple. The EMF developed is known as the thermoelectric EMF. And the current through the circuit is called 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 pair of metals arranged them 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

• The Seebeck coefficient is a measure of the amount of potential induced per difference in temperature. S is one of the transport properties of the material used.

• The Seebeck coefficients generally vary with the temperature and the Seebeck coefficient depends on the composition of the conductor. Generally, the Seebeck coefficient at room temperature ranges from -100V/K to 1000V/K.

Application of Seebeck Effect:

There are many properties of the materials that vary with temperatures. The Seebeck effect will be a useful tool for monitoring the thermoelectric effects. Following are the few applications of the Seebeck effect:

1. The Seebeck effect is used in thermoelectric generators. Thermoelectric generators are used in power plants where it converts waste heat into electricity.

2. The Seebeck effect is used in automobiles as an automotive generator or an automotive thermoelectric generator that will help in increasing fuel efficiency.

3. The Seebeck effect is used in thermocouples. The thermocouples are electrical devices made of two dissimilar metals or conductors placed at two different temperatures. These are used to measure the potential difference developed between the two conductors.

4. The Seebeck effect is also used in thermophiles. The thermophiles are the number of thermocouples connected in series.

Did You Know?

In thermal plants, we know that heat energy is converted into electrical energy and is later distributed according to the need through powerlines. While converting heat energy into electrical energy we will encounter some energy loss. Then, The Seebeck effect is used in such thermoelectric generators. These thermoelectric generators are used in power plants where it converts waste heat into electricity.