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What is the disadvantage of Maxwell Bridge?
Inductance cannot be measured over a wide range
Measurement is not independent of frequency
Number of components is large
Inductance can be measured over a wide range
Inductance cannot be measured over a wide range
Quick Summary: The Maxwell bridge is an AC bridge used to measure an unknown inductance in terms of a known capacitor. A primary disadvantage is its limited range, as it cannot be used to measure low Q-factor inductors effectively nor cover a very wide range of inductances due to the variable components required.
The Maxwell bridge is an AC bridge used to measure an unknown inductance in terms of a known capacitor. A primary disadvantage is its limited range, as it cannot be used to measure low Q-factor inductors effectively nor cover a very wide range of inductances due to the variable components required.
LxтАЛ=R2тАЛR3тАЛC4тАЛ тАФ Inductance of the unknown coil in terms of bridge components
Q=╧ЙR4тАЛC4тАЛ тАФ Quality factor of the inductor measured by the bridge
The bridge operates by balancing the impedances of four arms. At balance, the product of opposite arms is equal. Since one arm contains a capacitor and a resistor in parallel to balance an inductor and resistor in series, the balance equations depend on the values of these components. If the inductor is low Q or requires large variations, the variable standard components (capacitor and resistor) become physically impractical or non-linear.
Used for measuring medium-Q inductors (1<Q<10).
Balance equations are independent of supply frequency.
Variable capacitor is generally more expensive/complex than variable resistors.
Limited effectiveness for low Q coils because R4тАЛ becomes excessively high.
Frequency independent balance equations
Useful for comparing inductances
No frequency error due to series resistance
Cannot measure over a wide range of inductances
Requires a high-quality variable capacitor
Not suitable for low Q coils
Calibration of variable capacitor is difficult
Laboratory measurement of unknown inductors
Determination of magnetic properties of materials
The bridge is specifically named after James Clerk Maxwell.
Option B is incorrect because the balance equations for a Maxwell bridge do not contain the frequency term ╧Й in the final result (LxтАЛ=R2тАЛR3тАЛC4тАЛ), making it frequency independent.
A is correct тАФ The Maxwell Bridge is not suitable for measuring inductances over an extremely wide range, especially low Q-factor inductors, due to the physical limitations of the required variable components.
Always remember that while Maxwell bridge is frequency independent, Hay's bridge is a modification of Maxwell's bridge specifically designed for high Q-factor inductors.