# MCQs on Velocity Sensors

1 - Question

Which type of velocity sensor has a fixed permanent magnet attached to it?
a) Pyroelectric type
b) Piezoelectric type
c) Moving coil type
d) Stationary coil type
Explanation: Moving coil type of velocity sensor has a fixed permanent magnet attached to it. The coil inside it has a relative motion with respect to the stationary magnet. When the coil is in motion, an electromagnetic force is induced in the coil due to electromagnetic induction. This electromagnetic force is proportional to the velocity of the moving object.

2 - Question

What is the unit in which tachometers measure velocity?
a) Revolution per minute
b) Meter per second
c) Kilometer per hour
d) Rotation per minute
Explanation: Tachometers measure velocity in Revolution per minute (RPM). They also act as revolution counters, (i.e) they can also count the number of revolution an object has made in the required interval of time.

3 - Question

Which type of tachometer contain primary and secondary stators with fixed windings?
a) AC tachometers
b) DC tachometers
c) Alternating tachometers
d) Brushless tachometers
Explanation: AC tachometers contain primary and secondary stators with fixed windings. It provides fixed output voltage when the rotor is stationary and varying voltage only when the rotor is moving, this varying voltage is proportional to the velocity of the revolving object.

4 - Question

For what purpose, a “tachometer” is used?
a) It is used for calculating velocity in revolution per minute
b) It is used for calculating the number of revolutions
c) It is used for calculating velocity in revolution per second
d) It is used for calculating the velocity in rpm and number of revolutions
Explanation: Tachometer is used to calculate velocity in revolution per minute. It can also be used as a revolution counter to calculate the number of revolutions the object has made which we have taken into consideration.

5 - Question

The Laser surface velocimeter works on dopplers principle.
a) True
b) False
Explanation: The Laser surface velocimeter(LSV) works on dopplers principle or the dopplers effect. According to dopplers effect, there is change in the intensity of wave (here light wave) when the source and observer move towards or away from each other.

6 - Question

Accelerometer can be used to measure the tilt.
a) True
b) False
Explanation: In addition of measuring the inertial measurement of velocity and position, accelerometers can be also used to measure the degree of tilt by considering the acceleration due to gravity as reference. These are generally used in self balancing robots.

7 - Question

What does RPM stand for?
a) Rotation per minute
b) Revolution per minute
c) Rounds per minute
d) Rotation per millisecond
Explanation: RPM stands for revolution per minute. It is the most commonly used unit in motor appliances and motor vehicles for denoting the speed of the crank shaft in the engine.

8 - Question

_______ velocity sensor is a type of velocity sensor
a) Infrared
b) Proximitor
c) Piezoelectric
d) Ultrasonic
Explanation: Piezoelectric velocity sensor is a type of velocity sensor. The output of the velocity sensor is proportional to the velocity of the object. Since the output of the sensor is very small so it mostly needs an amplifier for using it for any application.

9 - Question

LSV in terms of velocity measurement stands for ________
a) Laser Surface Velocimeter
b) Laser Surface Velocity meter
c) Linear Surface Velocimeter
d) Linear Surface Velocity meter
Explanation: LSV in terms of velocity measurement stands for Laser surface velocimeter. It is a non-contact type velocity measuring tool which uses the laser doppler effect for evaluating the light scattered from the moving object.

10 - Question

Which is a type of velocity sensor?
a) MSP430G2ET
b) CMCP793V-500
c) MPU 6050
d) L298N