# Instrumentation Transducers Questions and Answers – Electro Mechanical Systems

This set of Basic Instrumentation Transducers Questions and Answers focuses on “Electro Mechanical Systems”.

1. Tacho generators are ______________
a) Zero-order system
b) First-order system
c) Second order system
d) None of the mentioned

Explanation: Zero-order systems have a constant transfer function. Tacho-generators are working based on induced emf due to the movement of conductors in a magnetic field, developed speed will be proportional to speed and hence transfer function will have a constant value.

2. Current to force and current to torque conversion is possible only for a constant current source.
a) True
b) False

Explanation: For consistent and stable conversion of current to mechanical quantities constant current supply is required.

3. Which of the following represents transfer function of tacho-generators?
a) Kg
b) 1/Kg
c) SKg
d) S2Kg

Explanation: Tacho generators are zero order systems, in which transfer function will be a constant value. Kg represents generator constant or back emf constant.

4. Transfer function of force motor is _____________
a) Kg
b) SKg
c) Kf
d) SKf

Explanation: Transfer function of force motor is a constant term since, it is a zero-order system. Kf stands for force constant.

5. Most electrical indicating instruments are electromechanical systems since ________________
a) They are used to measure electric component
b) They are more precise
c) They require no external power to operate
d) They convert electrical quantity to mechanical quantity

Explanation: Electromechanical systems are which converts electrical quantity to mechanical quantity. Most electronic indicating instruments works on this principle, and they are electromechanical instruments.

6. Torque developed by a DC motor will be proportional to armature current.
a) True
b) False

Explanation: In a DC motor armature current is the essential part of producing rotatory motion, and armature current will be directly proportional to torque output.

7. Which of the following is the correct conversion in an electro mechanical system?
a) Electrical to electrical
b) Electrical to mechanical
c) Mechanical to electrical
d) Both electrical to mechanical and mechanical to electrical

Explanation: Electro mechanical systems convert electrical quantity to mechanical quantity and vice versa.

8. For a constant field dc motor, what is the relation between the mechanical time constant and armature resistance?
a) Direct proportionality
b) Inverse proportionality
c) Double
d) Equal

Explanation: Mechanical time constant is given by relation JR / K2, in which R is the armature resistance.

9. Which of the following represents for torque speed characteristic for dc motor?
a) Positive slope
b) Negative slope
c) Slope zero
d) None of the mentioned

Explanation: Torque speed characteristic of a dc motor has a negative slope with slope Kt/R, is essential for a motor to come to rest when the applied voltage is made zero.

10. What is the relation between eddy current damping coefficient and resistance in PMMC device?
a) Direct proportionality
b) Inverse proportionality
c) Constant
d) None of the mentioned

Explanation: In PMMC devices eddy current damping ratio and resistance shows inverse proportionality. As resistance increases, the damping ratio decreases.

Sanfoundry Global Education & Learning Series – Instrumentation Transducers.

To practice basic questions and answers on all areas of Instrumentation Transducers, here is complete set of 1000+ Multiple Choice Questions and Answers.

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