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

This Section covers below lists of topics.

1. D’Arsonval Galvanometer
2. Construction of D’Arsonval Galvanometer
3. Dynamic behavior of Galvanometer
4. Response of Galvanometer
5. Operational Constants
6. Relative Damping
7. Logarithmic Decrement
8. Overshoot
9. Damping
10. Sensitivity
11. Galvanometer Shunts
12. Ballistic Galvanometer
13. Flux Meter
14. Vibration Galvanometer

PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE

#### 1. In d’Arsonval galvanometer, an iron core is usually used between the permanent magnet pole faces. This is used so that

• Flux density in the air gap becomes high therby a large deflecting torque is produced
• The effect of stray magnetic fields is reduced
• Moment of inertia of moving parts becomes smaller.
• None of the above.

#### 2. Sometimes, d’Arsonval galvanometers, do not use ferromagnetic cores between poles of the permanent magnet. In this case

• The flux density becomes smaller resulting in low deflecting torque
• The dimension of moving coil can be made smaller thereby reducing the moment of inertia
• The magnetic field may not be radial resulting in a non-uniform scale even if spring control is used
• All the above

#### 3. A d’Arsonval galvanometer uses a light and scale arrangement.  The light source is placed 1 m away from the moving system of galvanometer. The arrangement uses a circular scale calibrated in mm. the deflection indicated by the scale is

• 1000mm
• 2000mm
• 500mm
• None of the above

#### 4. if a current of 1 µ A is passed through the coil. The spring stiffness is 2 × 10-6 Nm/rad and the displacement constant is 2 Nm/A. the time period of free oscillations in a galvanometer having a relative damping of 0.6 is 2 s. the frequency of damped oscillation is :

• None of the above

• 0.48
• 1.25
• 4.19
• -4.19

#### 6. In a critically damped galvanometer the deflection at a time 0.9 times the time of free oscillations after a current is passed through the moving coil is approximately

• 0.986 times the final deflection
• 0.901 times the final deflection
• 0.866 times the final deflection
• None of the above.

#### 7. The resistance required for critical damping in a circuit is 1000Ω. The galvanometer circuit has a resistance of 800 Ω. Is the galvanometer circuit :

• Underdamped
• Undamped
• Overdamped
• None of the above

• 0.9
• 1.11
• 4
• 2

#### 9. A circuit of 2 µ A is passed through the moving coil of an undamped d’Arsonval galvanometer which has a displacement constant of 2 Nm/A and a control constant of 10 ×10-6 Nm/rad. The moving oscillates with an amplitude of :

• None of the above.

• G2 / √KJ
• G / √KJ
• G / 2√KJ
• G2 / 2√KJ

• 0.25 mm/µV
• 0.25 mm/V
• 2.5 mm/ µV
• 250 mm/ µV

#### 12. Ayrton shunt is used in d’Arsonval galvanometers so as to limit the current in the galvanometer coil to its maximum permissible value. The relative value of current through the galvanometer coil and the shunt

• Depends upon the value of resistance of galvanometer coil only
• Depends upon the resistance of galvanometer coil and the shunt
• Does not depends upon the value of resistance of galvanometer coil
• None of the above.

#### 13. A ballistic galvanometer should be designed with

• Large period of natural oscillations and a negligible damping constant
• A small period of natural oscillations and high damping constant
• A large period of natural oscillations and a high damping factor
• Small period of natural oscillations and a low damping factor.

#### 14. In a flux meter

• The controlling torque is produced by weights attached to moving coil
• The controlling torque is produced by springs
• There is no controlling torque
• None of the above.

#### 15. In an unshunted flux meter,the sensitivity is dependent upon

• resistance of moving coil
• resistance of search coil
• resistance of both search and moving coil
• none of the above.

#### 16. A vibration galvanometer is to be turned to a frequency of 50 Hz. The ratio of its control constant to inertia constant should be

• 98696
• 2500
• 132 × 10-6
• None of the above.

#### 17. A vibration galvanometer is tuned

• By changing the length and tension of vibrating coil
• By attaching weights to vibrating coil
• By changing its damping constant
• All the above.

• Upto 50 Hz
• Upto 500 Hz.
• Above 500 Hz
• Upto 10KHz.

#### 19. A Duddell’s oscillograph will give no amplitude distortion and phase displacement if its

• Moment of inertia and stiffness constant are zero
• Stiffness constant and damping factor are zero
• Moment of inertia and damping factor are zero
• All the above.

#### 20. In a Duddell’s oscilloscope the phase displacement of fundamental and 13th harmonic are calculated to be 3° and 36° The oscillograph will show the 13th harmonic to be

• 39° ahead of its true position
• 38° ahead of its true position
• 3° ahead of its true position
• 3° behind of its true position.
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