Production of electricity by heat, Physics

Production of electricity by heat:

The Seebeck effect - the thermocouple.  When two different metals are brought into contact with one another, it is found that electrons can leave one of the metals more easily than they can leave the other metal.  This is because of the difference in what is known as the work function of the two metals.  Since electrons leave one metal and are gained by the other, a potential difference exists between the two metals; thus the emf is known as the contact potential or contact emf.

If two metals, say copper and iron, are joined at two points as shown in the diagram above, and both junctions are at the same temperature, the contact potentials cancel each other out and no current flows in the loop of wire.  However, Thomas Johann Seebeck (1770 -1831) discovered that if the two junctions are kept at different temperatures, there is a drift of electrons around the circuit, that is to say, current flows.

1189_production of electricity by heat.png

The magnitude of the voltage produced by this method is small - only a few millivolts per degree centigrade - but it is sufficient to be measured.  The current flow is a measure of the difference in temperature between the 'hot' junction and the 'cold' junction.

Each junction is known as a thermocouple and if a number of thermocouples are connected in series so that alternate junctions are 'hot' and the other junctions are 'cold', the total emf is increased; this arrangement is known as a thermopile.

On aircraft, thermocouples are used for temperature measurement and will be examined in more detail at a later date.

 

 

 

Posted Date: 9/13/2012 1:47:04 AM | Location : United States







Related Discussions:- Production of electricity by heat, Assignment Help, Ask Question on Production of electricity by heat, Get Answer, Expert's Help, Production of electricity by heat Discussions

Write discussion on Production of electricity by heat
Your posts are moderated
Related Questions
Questions: A source charge generates an electric field to exist in the region of space around that source charge. The electric field exerts a force on some test charge that fin

Wooden block sits on a level lab table. A string draped over a pulley connects to a bucket that can be filled with lead pellets. Maggie needs to measure how much applied mass (pell


WHY Surface tension increases when an highly soluble SUBSTANCE is dissolved in water WHILE IT DECREASES WHEN an weakly soluble substance is dissolved in water

How to convert from only a displacement vs time graph given, to velocity AND acceleration vs time graphs?

Two vibrating particles that are "out of phase" differ in the phase of their vibration by: a) 1/4 cycle b) 1/2 cycle c) 3/4 cycle d) 1 cycle Ans: Two vibra

If conductors carries current in similar direction, then force among them will be attractive. If conductor carries current in reverse direction, then force among them will be repul

application of huygen''principle

Q.   Describe the method of measurement of the thickness of a thin transparent mica slit using Fresnel's Bi-prism. Give necessary theory. Draw suitable diagram. Measurement of

A thin rod of length 1 m is fixed in a vertical position inside a train, which is moving horizontally with constant acceleration 4 m/s2. A bead can slide on the rod, and friction c