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The original design was a saturated cadmium cell producing a 1.018 638 V reference and had the advantage of having a lower temperature coefficient than the previously used Clark cell. [1] One of the great advantages of the Weston normal cell is its small change of electromotive force with change of temperature.
Solar cell output voltage for two light-induced currents I L expressed as a ratio to the reverse saturation current I 0 [52] and using a fixed ideality factor m of 2. [53] Their emf is the voltage at their y-axis intercept. Solving the illuminated diode's above simplified current–voltage relationship for output voltage yields:
The Seebeck coefficients generally vary as function of temperature and depend strongly on the composition of the conductor. For ordinary materials at room temperature, the Seebeck coefficient may range in value from −100 μV/K to +1,000 μV/K (see Seebeck coefficient article for more information).
Cell diagram. Pt(s) | H 2 (1 atm) | H + (1 M) || Cu 2+ (1 M) | Cu(s) E° cell = E° red (cathode) – E° red (anode) At standard temperature, pressure and concentration conditions, the cell's emf (measured by a multimeter) is 0.34 V. By definition, the electrode potential for the SHE is zero. Thus, the Cu is the cathode and the SHE is the ...
A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property R that changes when the temperature changes by dT , the temperature coefficient α is defined by the following equation:
The data below tabulates standard electrode potentials (E°), in volts relative to the standard hydrogen electrode (SHE), at: . Temperature 298.15 K (25.00 °C; 77.00 °F); ...
E red is the half-cell reduction potential at the temperature of interest, E o red is the standard half-cell reduction potential, E cell is the cell potential (electromotive force) at the temperature of interest, E o cell is the standard cell potential, R is the universal ideal gas constant: R = 8.314 462 618 153 24 J K −1 mol −1, T is the ...
The design had two drawbacks—a rather large temperature coefficient of −1.15 mV/°C, and corrosion problems caused by the platinum wires alloying with the zinc amalgam connections where they enter the glass envelope. [citation needed] In 1905, Clark cells were supplanted as a voltage standard by the more temperature-independent Weston cell. [1]