This set of Tough Electrical Measurements Questions and Answers focuses on “Advanced Problems on Measurement of Inductance using AC Bridges”.

1. In the Owen’s bridge shown in below figure, Z_{1} = 200∠60°, Z_{2} = 400∠-90°, Z_{3} = 300∠0°, Z_{4} = 400∠30°. Then the _______

a) Bridge is balanced with given impedance values

b) Bridge can be balanced, if Z_{4} = 600∠60°

c) Bridge can be balanced, if Z_{3} = 400∠0°

d) Bridge cannot be balanced with the given configuration

2. In Maxwell’s capacitance bridge for calculating unknown inductance, the various values at balance are, R_{1} = 300 Ω, R_{2} = 700 Ω, R_{3} = 1500 Ω, C_{4} = 0.8 μF. Calculate R_{1}, L_{1} and Q factor, if the frequency is 1100 Hz.

a) 240 Ω, 0.12 H, 3.14

b) 140 Ω, 0.168 H, 8.29

c) 140 Ω, 0.12 H, 5.92

d) 240 Ω, 0.36 H, 8.29

3. In Wein’s bridge, the output frequency is determined by __________

a) RLC combination

b) LC combination

c) RC combination

d) RL combination

4. What is the disadvantage of Maxwell Bridge?

a) Inductance cannot be measured over a wide range

b) Measurement is not independent of frequency

c) Number of components is large

d) Inductance can be measured over a wide range

5. The Bridge shown in the below figure is ______________

a) Maxwell’s Bridge

b) Wien’s Bridge

c) Anderson’s Bridge

d) Hay’s Bridge

6. Hay’s Bridge is used for measuring __________

a) Resistance in the milliohm range

b) Low values of capacitance

c) Comparison of resistances which are nearly equal

d) The Inductance of a coil with a large time constant

7. In Maxwell’s Bridge, as shown in the figure below, the values of the resistance R_{1} and inductance L_{1} of a coil are to be calculated after the bridge is balanced. The values are?

a) 375 Ω and 75 mH

b) 75 Ω and 150 mH

c) 37.5 Ω and 75 mH

d) 75 Ω and 75 mH

8. Maxwell’s Inductance Capacitance Bridge is used for measuring ___________

a) Inductance

b) Capacitance

c) Frequency

d) Mutual Inductance

9. The four arms of an AC bridge network are as follows:

Arm AB: unknown impedance Arm BC: standard capacitor C_{2}of 1000pf Arm CD: a non-inductive resistance of R of 100 Ω in parallel to a capacitor of 0.01 μF Arm DA: a non-inductive resistance of 1000 Ω

The supply frequency is 50 Hz and connected across terminals B and D. If the bridge is balanced with the above value, determine the value of unknown Impedance.

a) 10 kΩ

b) 100 kΩ

c) 250 kΩ

d) 20 kΩ

10. The four arms of an AC bridge network are as follows:

Arm AB: unknown impedance Arm BC: standard capacitor C_{2}of 1000pf Arm CD: a non-inductive resistance of R of 100 Ω in parallel to a capacitor of 0.01 μF Arm DA: a non-inductive resistance of 1000 Ω

The supply frequency is 50 Hz and connected across terminals B and D. If the bridge is balanced with the above value, determine the value of unknown Capacitance.

a) 100 pf

b) 1000 pf

c) 500 pf

d) 10 pf