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Question Detail
Inductance comparison bridge is used to compute
Options
Option A: Unknown inductance and resistance
Option B: Unknown resistance
Option C: Unknown inductance
Option D: Unknown capacitance
Correct Answer
Unknown inductance and resistance
Solution & Explanation
{"type":"technical","methodBadge":"Concept & Principle","explanation":"An Inductance Comparison Bridge is a modified Wheatstone bridge circuit used to measure an unknown self-inductance by comparing it with a known standard inductance. Because practical inductors are not ideal and possess inherent winding resistance, the bridge simultaneously determines both the unknown inductance and its associated series resistance.","workingPrinciple":"The bridge operates by balancing four arms: one containing the unknown inductor with its internal resistance, one containing a high-quality standard inductor with an adjustable resistor, and two non-inductive ratio arms. Under null conditions, the bridge is balanced such that the product of impedances of opposite arms is equal ($Z_1Z_4 = Z_2Z_3$). Since both arms contain resistance and inductance, balance is achieved by adjusting both a standard variable resistor and the variable standard inductor simultaneously.","diagramSvg":"Inductance Comparison Bridge$Z_1 Z_4 = Z_2 Z_3$(Balance Condition)$L_x, R_x$$L_s, R_s$Unknown vs Standard Inductance","keyFormulas":["$L_x = L_s \\frac{R_2}{R_3}$ тАФ Balancing equation for inductance","$R_x = R_s \\frac{R_2}{R_3}$ тАФ Balancing equation for resistance"],"keyPoints":["The bridge requires a known standard inductor ($L_s$) which is often expensive and bulky.","Balance is achieved by adjusting $R_s$ and $L_s$ to nullify the detector current.","It is primarily used for the measurement of inductors with medium Q-factors.","Unlike the Maxwell Bridge, it uses a standard inductor rather than a capacitor."],"advantages":["Balance equations are independent of the supply frequency.","Can be used to measure inductors over a wide range of values."],"disadvantages":["Requires a high-quality standard variable inductor, which is costly.","More complex to construct than capacitance-based bridges like the Maxwell or Hay bridge."],"applications":["Precision measurement of self-inductance in laboratories.","Standardizing inductors used in calibration circuits."],"comparisonTable":[],"additionalInfo":["The bridge is essentially a variation of the Wheatstone bridge where resistances are replaced by complex impedances.","Option D is incorrect because capacitance measurement requires a Schering or Wien bridge, not an inductance comparison bridge."],"answer":"A is correct тАФ The inductance comparison bridge measures both the unknown inductance and its associated internal series resistance by balancing against a known standard inductor.","correctedOptions":["Unknown inductance and resistance","Unknown resistance","Unknown inductance","Unknown capacitance"],"coreConcepts":["AC Bridge Circuits","Complex Impedance Balancing","Self-Inductance Measurement"],"crossTopicTip":"Always remember that in AC bridges, the balance condition involves both magnitude and phase, requiring the adjustment of two variables (usually a resistor and an inductor/capacitor) to satisfy both real and imaginary components."}