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What is Wheatstone bridge ? Explain its principle.
Solution
Wheatstone bridge is special network of four resistors and battery connected as shown in figure below.
Four resistors $\mathrm{R}_{1}, \mathrm{R}_{2}, \mathrm{R}_{3}$ and $\mathrm{R}_{4}$ are connected with battery as shown in figure.
Battery is connected between $\mathrm{A}$ and $\mathrm{C}$ called battery arm.
Galvanometer is connected between $\mathrm{B}$ and $\mathrm{D}$ hence, it is called galvanometer arm.
Consider battery is to be ideal (zero internal resistance).
Current flowing in resistor $\mathrm{R}_{1}, \mathrm{R}_{2}, \mathrm{R}_{3}$ and $\mathrm{R}_{4}$ be $\mathrm{I}_{1}, \mathrm{I}_{2}, \mathrm{I}_{3}$ and $\mathrm{I}_{4}$ respectively.
Current will be flowing through all four resistors and galvanometer.
In special condition when current through galvanometer is zero $(1 \mathrm{~g}=0)$ Wheatstone bridge is
said to be in balanced condition.
In balanced condition of Wheatstone bridge $\mathrm{I}_{1}=\mathrm{I}_{3}$ and $\mathrm{I}_{2}=\mathrm{I}_{4}$.
Similar Questions
In a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure
| $Sl$. $No$. | $R\, (\Omega )$ | $l\, (cm)$ |
| $1$. | $1000$ | $60$ |
| $2$. | $100$ | $13$ |
| $3$. | $10$ | $1.5$ |
| $4$. | $1$ | $1.0$ |
Which of the readings is inconsistent ?
