Question

If the PPM concentration of a gas that is being detected by the MQ2 Gas Sensor increases what will happen to its Digital Output pin?

(a) Voltage Increases

(b) Voltage Decreases

(c) Voltage becomes 0

(d) Voltage doesn’t change

The question was asked during an online interview.

This interesting question is from MQ2 Gas Sensor Module in division Interfacing of Sensors, Actuators, and Other Modules of Arduino

Answer 1

Right answer is (d) Voltage doesn’t change

Explanation: The MQ2 Gas Sensor has two output pins, one is digital and one is analog. The digital pin can only vary between two voltage levels which corresponds to 2 Logic Levels, 1 and 0 or 5V and 0V respectively. So if a gas is present then the digital output becomes 5V but cannot detect any kind of change in concentration of the gas.