Engineering Questions with Answers - Multiple Choice Questions

# MCQs on Sensor Interfacing

1 - Question

Which of the following is correct about the word sensors?
a) that senses something
b) it is a type of a transducer that converts one form of energy to another
c) it can produce output in the form of electrical pulses, current or voltage
d) all of the mentioned

Explanation: Sensors are the devices that are used to sense a particular thing by converting one form of energy into another, this converted form can be in the form of some analog output, or in the form of current or the voltage as the case may be.

2 - Question

Why do we need to apply the concept of signal conditioning to a sensor?
a) in order to convert it into a desirable form of energy
b) for testing
c) for sensing something
d) all of the mentioned

Explanation: Signal Conditioning is the concept that is used for data acquisition of the signal. For measuring and analyzing this value at a practical stage, by converting it into a desirable form of energy.

3 - Question

Which of the following is correct about LM35 based sensors?
a) its output voltage is directly proportional to the Celsius scale
b) its output voltage is directly proportional to the Fahrenheit scale
c) none of the mentioned
d) all of the mentioned

Explanation: LM35 based sensors are those sensors whose output voltage is directly proportional to the Celsius scale.

4 - Question

What is the difference between the LM34 and the LM35 based sensors?
a) one requires external calibration while other does not
b) one has output voltage proportional to the Celsius scale while others have to the Fahrenheit scale
c) one is fast other is slow
d) all of the mentioned

Explanation: LM35 has the output voltage proportional to the Celsius scale while the LM35 based sensors have output voltage proportional to the Fahrenheit scale.

5 - Question

Every transducer must be connected with the signal conditioning circuit?
a) true
b) false
c) can’t say
d) depends on the conditions

Explanation: For analyzing purposes, every transducer must be connected to a signal conditioning circuit in order to measure its value as a practical platform.

6 - Question

LM35 provides _______ V for each degree count?
a) 1
b) 0.1
c) 0.001
d) 10

Explanation: LM35 provides 10mV for every degree change of the Celsius scale.

7 - Question

Why for the 8 bit analog input we select Vref as the 2.56V?
a) to obtain each degree count as the 2.56V
b) to get 2.56V at the output
c) to obtain each degree count as the 10mV
d) to get 10mV as the output

Explanation: For an 8 bit analog input, each degree count is calculated as the Vref/256, so if Vref is selected as 2.56V then we can obtain 10mV for each degree count of the scale.

8 - Question

What is the temperature for LM35 sensor if the analog output is 0011 1001?
a) 3
b) 9
c) 57
d) 41

Explanation: The binary for the above output is 57, so in case of LM35 sensors we obtain the output as 57 C.

9 - Question

In an external hardware, there are how many pins available for the LM35 and the LM34 based sensors?
a) 2
b) 3
c) 10
d) 1

Explanation: LM35 consists of mainly 3 pins, they are Vcc, Gnd, analog output.

10 - Question

Do LM34 and LM35 based sensors have linear output?
a) yes
b) no
c) depends on the conditions
d) can’t say