# IOT Questions and Answers – Accelerometer and Gyroscope Sensor

This set of IOT Multiple Choice Questions & Answers (MCQs) focuses on “Accelerometer and Gyroscope Sensor”.

1. Which axis accelerometer is mostly used in IOT?
a) 2- axis
b) 3- axis
c) 1- axis
d) Combination of all

Explanation: It uses 3-axis accelerometer. It detect orientation, shake, tap, double tap, fall, tilt, motion, positioning, shock or vibration.

2. Accelerometer is the measurement of ________
a) Velocity/time
b) Energy/time
c) Height/time
d) Angle/time

Explanation: Accelerometer is the measurement of the change in velocity or speed divided by time. For example, a car accelerating from a standstill to 60mph in 60 seconds is determined to have an acceleration of 10mph per second(60/6).

3. What is the use of accelerometer in laptops?
a) To rotate the screen
b) To protect hard drives from damage
c) To get the angle on monitor
d) To get the linear acceleration

Explanation: Accelerometer in laptops protect hard drives from damage. If the laptop were to suddenly drop while in use, the accelerometer would detect the sudden free fall and immediately turn off the hard drive to avoid hitting the reading heads into the hard drive platter.

4. Are accelerometer used in cars?
a) True
b) False

Explanation: Accelerometers are likewise used in cars as the industry method of detecting car crashes and deploying airbags almost instantaneously.

5. How many and what are the parts that are present in the accelerometer sensor?
a) 1, capacitor sensor
b) 3, piezoelectric effect, Analog display, digital display
c) 2, piezoelectric effect and capacitor sensor
d) 2, Capacitor sensor, digital Display

Explanation: The accelerometer consists of many different parts and work in many ways, two of which are piezoelectric effect and the capacitor sensor. The piezoelectric effect is the most common form of accelerometer and uses microscopic crystal structures that become stressed due to accelerative forces.
The capacitance accelerometer senses changes in capacitance between micro structures located next to the device.
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6. The BGM160 gyroscope sensor is fitted with ________ interfaces.
a) Only SPI
b) Only I2C
c) SPI and UART
d) SPI and I2C

Explanation: The BGM160 is fitted with digital bi-directional SPI and I2C interfaces for optimum system integration, which require 3.3v operation.

7. Gyroscope is used for_________
a) Anti-theft
b) Capacitive proximity sensing
c) Gaming
d) Angle detection

Explanation: Gyroscope is mainly used in 3D mouse, games and athlete training. Gyroscope is also used in navigation, Remote control, notebooks and ultrabooks.

8. Gyroscope is used to measure_________
a) Linear Acceleration
b) Angular velocity
c) Angular velocity and linear acceleration
d) Linear velocity

Explanation: Gyroscope is used to measure angular velocity. Gyroscopes aimed to create smaller and more sensitive devices.

9. What is the rate noise density of gyroscope?
a) 0.011 dps/√Hz
b) 0.0011 dps/√Hz
c) 1.11 dps/√Hz
d) 11.1 dps/√Hz

Explanation: Gyroscopes offer superior stability over time and temperature, with a rate noise density up to 0.011 dps/√Hz. This guarantees the level of accuracy required by the most of the advanced motion-based applications.

10. How many sensing structures are there in gyroscope sensor?
a) Two structures
b) Three structures
c) Depending on application
d) Single structure

Explanation: The 3-axis gyroscopes have a single sensing structure for motion measurement along all three orthogonal axes, while other solutions on the market rely on two or three independent structures.

11. Theory behind working of accelerometer can be understood from ________
a) Rotary
b) Liner
c) Newtonian mechanism
d) Reciprocating

Explanation: Theory behind working of accelerometer can be understood from mechanical model of accelerometer, using Newtonian mechanics. The sensing element essentially is a proof mass.

12. ________ is included in a system to provide desirable damping effect.
a) Speedometer
b) Seismic
c) Damper
d) Dashpot

Explanation: A dashpot is also included in a system to provide desirable damping effect. The dashpot is attached between the mass and the casing.

13. Displacement and acceleration are related by fundamental scaling law.
a) True
b) False

Explanation: Displacement and acceleration are related by fundamental scaling law. A higher resonant frequency implies less displacement or low sensitivity.

14. ________ sensor is used for tracking rotation or twist.
a) Gyroscope
b) Temperature
c) Pressure
d) Proximity

Explanation: Accelerometers in mobile phones are used to detect the orientation of the phone. The gyroscope adds an additional dimension to the information supplied by the accelerometer by tracking rotation or twist.

15. Ring laser type gyroscope operates based on _________ principle.
a) Damper
b) Sagnac
c) Seismic
d) Dashpot

Explanation: Ring laser type gyroscope operates based on sagnac effect. Sagnac involves splitting a beam of light in two and sending them through different opposite paths and then creating interference between the two beams.

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