This Portion of Electrical andElectronic Measurements and Measuring instruments contains AC Bridges / Impedance Bridges MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.

**This Section covers below lists of topics.**

- A.C Bridges
- Measurement of Self-inductance
- Measurement of Capacitance
- Measurement of Mutual inductance
- Measurement of Frequency
- Universal impedance Bridge
- Source of errors in Bridge Circuits
- Wagner Earthing Devices
- Transformer Ratio Bridge

#### 1. Please check figures here to answer the Questions from 1-3. in order that the bridge shown in fig be balanced

- I
_{1 }= I_{3 }and I_{2 }= I_{4} - Z
_{1}Z_{4 }= Z_{2}Z_{3} **∠****θ**_{1 }+**∠****θ**_{4 }=**∠****θ**_{2 }+**∠****θ**_{3}- All of the above.

D. All of the above.

#### 2. For the bridge shown in figure above Z_{1 }= 200Ω ∠30°, Z_{2 }= 150Ω ∠0°, Z_{3 }= 250Ω ∠-40°. In order that the bridge can be balanced Z_{4 }should be :

- 187.5Ω ∠-70°
- 187.5Ω ∠-10°
- 333.3Ω ∠10°
- 120Ω ∠70°

A. 187.5Ω ∠-70°

#### 3. For the bridge shown in figure above , arm ab consists of resistance in series with an inductance, arms bc and ad consists of pure resistance. in order to achieve balance arm cd should consist of

- A variable resistance in series with an variable inductance
- A variable resistance
- A variable resistance in series or parallel with a variable capacitance
- A variable capacitance.

C. A variable resistance in series or parallel with a variable capacitance

#### 4. The equations under balance conditions for a bridge are :
R_{1} = R_{2} R_{3} / R_{4 }and L_{1 }= R_{2}R_{3}C_{4}
Where R1_{ } and L1 are respectively unknown resistance and inductance.
In order to achieve converging balance

- R
_{2 }and R_{3 }should be chosen as variables - R
_{2 }and C_{4 }should be chosen as variables - R
_{4 }and C_{4 }should be chosen as variables - R
_{3 }and C_{4 }should be chosen as variables

C. R

_{4 }and C_{4 }should be chosen as variables#### 5. Maxwell’s inductance-capacitance bridge is used for measurement of inductance of :

- Low Q coils
- Medium Q coils
- High Q coils
- Low and medium Q coils.

B. Medium Q coils

#### 6. The advantage of Hay’s bridge over Maxwell’s inductance-capacitance bridge is because

- Its equations for balance do not contain any frequency term
- It can be used for measurement of inductance of high Q coils
- It can used for measurement of inductance of low Q coils
- None of the above.

B. It can be used for measurement of inductance of high Q coils

#### 7. In D’Sauty’s bridge (unmodified form) it is :

- Possible to obtain balance even if both the capacitors are imperfect
- Possible to obtain balance if one of the capacitors is perfect
- Possible to obtain balance only if both the capacitors are perfect
- All the above.

C. Possible to obtain balance only if both the capacitors are perfect

#### 8. Frequency can be measured by using :

- Maxwell’s bridge
- Schering bridge
- Heavyside Campbell bridge
- Wien’s bridge.

D. Wien’s bridge.

#### 9. A bridge circuit works at a frequency of 2 kHz. The following can be used as detectors for detection of null conditions in the bridge

- Vibration galvanometer and headphones
- Headphones and tunable amplifiers
- Vibration galvanometers and tunable amplifiers
- Vibration galvanometers, headphones and tunable amplifiers.

B. Headphones and tunable amplifiers

#### 10. Wagner’s Earth devices are used in a.c bridge circuit for :

- Eliminating the effect of earth capacitances
- Eliminating the effect of inter-component capacitances
- Eliminating the effect of stray electrostatic fields
- Shielding the bridge elements.

A. Eliminating the effect of earth capacitances

#### 11. A bridge circuit works at a frequency of 2 kHz. Which of the following can be used as null detector in such a bridge?

- Vibration galvanometers and tunable amplifiers
- Headphones and tunable amplifiers
- Vibration galvanometers and headphones
- All of the above

B. Headphones and tunable amplifiers

#### 12. Under balanced condition of a bridge for measuring unknown impedance, if the detector is suddenly taken out

- measured value of the impedance will be lower
- measured value of the impedance will be higher
- measured value of the impedance will not change
- the impedance can not be measured

C. measured value of the impedance will not change

#### 13. Harmonic distortions in power supply does not affect the performance of Maxwell’s bridge since

- filters are used to remove harmonics
- final expression for unknown inductance contain only fundamental frequency
- mechanical resonance frequency of null detectors are beyond the range of harmonic frequencies
- final expression for unknown inductance is independent of frequency

D. final expression for unknown inductance is independent of frequency

#### 14. Maxwell’s bridge can be used for measurement of inductance with

- high Q factors
- very low Q factors
- medium Q factors
- wide range of Q factor variations

C. medium Q factors

#### 15. The advantage of Hay’s bridge over Maxwell’s inductance–capacitance bridge is that

- its final balance equations are independent of frequency
- it reduces cost by not making capacitor or inductor as the variable parameters
- it can be used measuring low Q inductors
- it can be used measuring high Q inductors

D. it can be used measuring high Q inductors

#### 16. The advantage of Anderson’s bridge over Maxwell’s bridge is that

- its final balance equations are independent of inductor losses
- it reduces cost by not making capacitor or inductor as the variable parameters
- number of bridge components required are less
- attaining balance condition is easier and less time consuming

B. it reduces cost by not making capacitor or inductor as the variable parameters

#### 17. The main advantage of Owen’s bridge for measurement of unknown inductance is that

- it has two independent elements R and C for achieving balance
- it can be used for measurement of very high Q coils
- it is very inexpensive
- it can be used for measurement of unknown capacitance as well

A. it has two independent elements R and C for achieving balance

#### 18. DeSauty’s bridge is used for measurement of

- high Q inductances
- low Q inductances
- loss less capacitors
- capacitors with dielectric losses

C. loss less capacitors

#### 19. Schering bridge can be used for measurement of

- capacitance and dissipation factor
- dissipation factor only
- inductance with inherent loss
- capacitor but not dissipation factor

A. capacitance and dissipation factor

#### 20. Frequency can be measured using

- Anderson’s bridge
- Maxwell’s bridge
- De Sauty’s bridge
- Wien’s bridge

D. Wien’s bridge