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In 1821 Thomas Seebeck, a German physicist discovered that when two dissimilar metal ( Seebeck used copper and bismuth) wires are joined at two ends to form a loop, a voltage is developed in the circuit if the two junctions are kept at different temperatures. The pair of metals forming the circuit is called a thermocouple . The effect is due to conversion of thermal energy to electrical energy. |
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The existence of current in the closed circuit may be confirmed by |
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the deflection of a magnetic needle caused by the magnetic field of the current |
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Joule heating produced in the wires |
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closing the circuit with a capacitor to accumulate measurable charge |
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placing a sensitive ammeter or a galvanometer in the circuit |
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measuring the amount of chemiucal deposit at the electrodes of an electrochemical cell. |
