Electrical Measurements Questions and Answers for Campus interviews on “Advantages and Limitations of Maxwell Bridge”.

1. What is the significance of the balance equation on losses?

a) independent of losses in inductance

b) independent of losses in capacitance

c) independent of losses in resistance

d) independent of losses in the circuit

Answer: a

Clarification: The balance equation in a Maxwell inductance capacitance bridge is independent of the losses associated with an inductance. According to the balance equation the unknown inductance is computed as L_{x} = R_{2} R_{3} C_{1}.

2. Balance equation is dependent on frequency.

a) True

b) False

Answer: b

Clarification: The balance equation in a Maxwell inductance capacitance bridge is independent on the measurement of frequency. The balance equation does not contain frequency terms such as ω and as a result, it is independent of frequency.

3. How can R_{1} be scaled?

a) by using a scale

b) by using an ohmmeter

c) by calibration

d) by using a galvanometer

Answer: c

Clarification: The resistance R_{1} in a Maxwell inductance capacitance bridge can be scaled through calibration. The value of the Quality factor Q can be read directly through calibration.

4. Scale of resistance can be calibrated.

a) True

b) False

Answer: a

Clarification: The resistance R_{1} in a Maxwell inductance capacitance bridge can be calibrated directly. As a result the value of the unknown inductance can be read directly.

5. Bridge can be used for the measurement of _________

a) high Q values

b) intermediate Q values

c) very low Q values

d) low Q values

Answer: d

Clarification: A Maxwell inductance capacitance bridge can be used for the measurement of low Q values only of the order of 1 to 10. This is because at high Q factor values the angular balance condition is not satisfied.

6. The balance condition is _________

a) is easy to obtain

b) is difficult to obtain

c) can’t be obtained

d) exists always

Answer: b

Clarification: The balance condition in a Maxwell inductance capacitance bridge is difficult to obtain. This occurs due to an interaction between resistance and reactance components in the bridge circuit.

7. Commercial Maxwell bridges measures _________

a) inductances in the range of 1 to 1000H

b) capacitances in the range of 10mF to 1F

c) resistances in the range of 0.001 Ω to 1Ω

d) power in the range of 1W to 50MF

Answer: a

Clarification: Basically a Maxwell bridge is used for the measurement of inductance in terms of known standard capacitance value. Inductances in the range of 1 to 1000H with an accuracy range of ±2% can be measured.

8. At high Q values, the angular balance condition is _________

a) satisfied

b) not satisfied

c) independent of Q factor

d) partially affected

Answer: b

Clarification: For high Q factor values in a Maxwell inductance capacitance bridge, the angular balance condition is affected. The relation θ_{1} + θ_{4} = θ_{2} + θ_{3} is not satisfied at high Q factor values. This occurs as θ_{4} reaches 90°. θ_{1} must become –90° as per the angular balance condition. But for this the value of R_{1} should be very high, which is not practically feasible.

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