Maxwell bridge is used to measure

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Inductance

Explanation: The Maxwell bridge is a modified Wheatstone bridge used to measure an unknown inductance by comparing it with a known variable standard capacitor. It is specifically designed for inductors having a medium Q-factor (typically 1

Working Principle: The bridge operates on the principle of null detection under AC excitation. By balancing the bridge such that the product of impedances of opposite arms is equal, the unknown inductance $L_x$ and its series resistance $R_x$ are determined. Since it uses a capacitor as the standard, it avoids the errors associated with stray magnetic fields and bulkiness found in variable standard inductors.

Key Formulas: $L_x = R_2 R_3 C_4$ — Inductance calculation formula; $R_x = \frac{R_2 R_3}{R_4}$ — Resistance of the inductor coil; $Q = \omega R_4 C_4$ — Quality factor of the coil

Key Points: Used for medium Q-factor inductors (1 to 10).; Uses a variable standard capacitor instead of a standard inductor.; The balance equation is frequency-independent.; Not suitable for low Q coils (use Hay's bridge) or very high Q coils (use Anderson bridge).

Advantages: Balance equation is independent of frequency.; Uses a standard capacitor which is more precise and compact than a standard inductor.

Disadvantages: Not suitable for high Q coils ($Q > 10$).; Requires a variable capacitor which can be expensive.

Applications: Industrial measurement of inductance in AC circuits.; Quality control in manufacturing of inductors.

Additional Info: For low Q coils ($Q. Option A (Resistance) is measured using Wheatstone bridge; Option C (Capacitance) is measured using Schering or De Sauty's bridge; Option D (Frequency) is measured using Wien's bridge.

Answer: B is correct — The Maxwell bridge is an AC bridge configuration primarily used to measure an unknown inductance by comparing it with a known variable capacitor.

Exam Tip: Remember that Maxwell's bridge is for medium Q, Hay's for high Q ($Q > 10$), and Anderson's bridge is the most precise for a wide range of Q factors.

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