CIRCUITOS DE CORRIENTE CONTINUA

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Combinaciones de resistencia

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Generalizando

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Solución

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Consultar sobre el Amperímetro, Voltímetro y Óhmetro

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The Wheatstone Bridge

An unknown resistance value can be accurately measured using a circuit known as a

Wheatstone bridge (Fig. 28.25). This circuit consists of the unknown resistance Rx ,

three known resistances R1 , R2 , and R3 (where R1 is a calibrated variable resistor),

a galvanometer, and a battery. The known resistor R1 is varied until the galvanometer

reading is zero—that is, until there is no current from a to b. Under this condition the

bridge is said to be balanced. Because the electric potential at point a must equal the

potential at point b when the bridge is balanced, the potential difference across R1 must

equal the potential difference across R2 . Likewise, the potential difference across R3must equal the potential difference across Rx . From these considerations we see that

Dividing Equation (1) by Equation (2) eliminates the currents, and solving for Rx , we find that

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