Question

The Wheatstone bridge is an arrangement of four resistances, say \(R_1, R_2, R_3\), and  \(R_4\). The null point condition is given by:

• A. \(\quad \frac{R_1}{R_2} = \frac{R_3}{R_4} \\\)
• B. \(\quad R_1 + R_2 = R_3 + R_4 \\\)
• C. \(\quad R_1 - R_2 = R_2 - R_4 \\\)
• D. \(\quad R_1 \times R_2 = R_3 \times R_4\)

Answer 1

The Correct Option is A

The Wheatstone bridge circuit facilitates the measurement of unknown resistances by achieving a balance between two bridge legs. Utilizing four resistors, denoted as \(R_1\), \(R_2\), \(R_3\), and \(R_4\), the bridge's balanced state, or null point condition, is established. At this equilibrium, a meter indicates zero deflection. The null point condition is mathematically expressed as:

\[\frac{R_1}{R_2} = \frac{R_3}{R_4}\]

This equation signifies that the resistance ratio on one side of the bridge equals that on the opposite side. This principle is instrumental for calculating an unknown resistance when the other three are known, thus rendering the Wheatstone bridge a crucial instrument for electrical measurements.