This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ... of the conductor and the change in its resistance, the temperature may be calculated. Such an instrument is often called a pyrometer. For use at high temperatures, carbon must be sealed away from air to prevent its combustion. For measuring very small differences of temperature, the bolometer has been found ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ... of the conductor and the change in its resistance, the temperature may be calculated. Such an instrument is often called a pyrometer. For use at high temperatures, carbon must be sealed away from air to prevent its combustion. For measuring very small differences of temperature, the bolometer has been found wonderfully sensitive. 813. What is the bolometer? The common form of bolometer consists of two similar circuits containing conductors of a material whose resistance changes rapidly with changes of temperature; these are arranged so that one may be exposed to the source of heat under investigation, while the other is protected from it. The two circuits are connected respectively to the two coils of a differential galvanometer which are wound or connected oppositely so that the needle is only affected by the difference between the currents in the two coils. When both circuits are connected to the same battery and both are at the same temperature, equal currents flow through the two coils and the needle is not affected; but if the temperature of one is different from that of the other, their resistances vary and the currents no longer balance, thus causing a deflection of the needle. Such instruments have been made so sensitive as to be affected by the heat from a candle a mile distant and even to show the heat from the distant stars. 814. Upon what principle was the Howell lamp indicator made? It depended upon the fact that the resistance of most metals increases with rise of temperature, while that of carbon decreases. Two circuits are arranged so that when equal or proportional currents flow in each, one neutralizes the effect of the other upon a galvanometer or other current indicator. One circuit contains a carbon resistance consisting of a special i...
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Add this copy of Electrical Catechism: an Introductory Treatise on to cart. $22.29, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2021 by Legare Street Press.
Add this copy of Electrical Catechism: an Introductory Treatise on to cart. $33.45, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2021 by Legare Street Press.
