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Function Measure of the intensity of current. |
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Description The instrument rests on a base of black glass or ebonite, with a back foot and two leveling screws. The magnet is vertical with polar expansions and a central nucleus of ductile iron. The upper suspension is a bronze ribbon and the bottom one is helical with an elastic thread. The tension of the ribbon is adjustable from above. With a 400 ohm coil the sensibility is 40 mm per microampere with the scale at one meter. The instrument is protected with a prismatic glass case fixed on the base, but the forward glass is mobile. | |||
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Function Measure of the intensity of current. |
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Description A frame sliding along a vertical column can be brought in correspondence with a turning magnetic bar on the horizontal cutter (knife - edge) provided with a long index. The multiplier has two wirings: one with a large wire with little resistance and one with a thin wire with great resistance. All the galvanometer turns on a tripod with adjustable screws. | |||
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Function Measure of electric currents. |
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Description A helical spring holds a conic nucleus made of a thin plate of iron. This controls a long equilibrated index. It is suspended in proximity of the axe of a bobbin. When the current passes the nucleus is sucked inside, and the shift is proportional to the intensity of the current. The two ends of the coil end at the terminals fixed on the base, and the left terminal can be put in communication with a resistance placed in parallel on the circuit of the bobbin. If the current travels only in the latter, we read the upper scale (0 - 2) A; if the current bifurcates, the indications of the instrument are multiplied by five (and at that moment we must read the lower scale 0-10 A). In this second case, in fact, only a fifth of the current crosses the coil. | |||
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Function Measure of potential differences. |
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Description The coil has an end united to the right terminal, while the other side ends on a plate of brass that can be connected to the left terminal. Between the plate and the terminal a bobbin is inserted, the resistance of which is four times that of the coil. If that resistance is excluded, the current travels only in the coil and the upper scale provides the indications. If we take the plug off, the total resistance becomes five times that of the coil and the indications must be multiplied by five (lower scale). | |||
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Function Measuring the radiant energy. |
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Description It is based on the variation of the electric resistance of an iron darkened grating, subjected to the heating radiations. The variations of the resistance are measured with the method of the bridge. The apparatus is indispensable for the examination of the thermal propriety of the spectrum. | |||
