# Arduino Questions and Answers – LM35 Temperature Sensor Module

This set of Arduino Questions & Answers for Exams focuses on “LM35 Temperature Sensor Module”.

1. What is the use of the LM35 Temperature Sensor Module?
a) Object Identification
b) To provide 3G Connectivity
c) To measure temperature
d) To measure Wi-Fi strength
View Answer

Answer: c
Explanation: The LM35 Temperature sensor module is used for measuring the temperature in the immediate surroundings of the sensor. The output of the sensor is an analog voltage which is proportional to the Celsius temperature scale.

2. How many terminals does the LM35 Temperature Sensor Module have?
a) 1
b) 3
c) 2
d) 4
View Answer

Answer: b
Explanation: The LM35 Temperature Sensor Module has 3 terminals which correspond to the GND or ground, the VCC which acts as voltage input, and OUT which puts out the output voltage of the sensor corresponding to the temperature.

3. What is the sensitivity of the LM35 Temperature Sensor Module?
a) 10mV/°C
b) 1mV/°C
c) 23mV/°C
d) 12mV/°C
View Answer

Answer: a
Explanation: The sensitivity per unit centigrade of the LM35 Temperature Sensor Module is the smallest degree change in temperature that corresponds to a change in the voltage reading on the sensor module.
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4. What will happen if we supply a voltage of 250V to the Vcc of the LM35 Temperature Sensor Module?
a) Damage is caused
b) Module will shut down
c) Module will not respond for the time the voltage is applied
d) Module will function normally
View Answer

Answer: a
Explanation: The LM35 Temperature Sensor Modules are mostly built to work on a voltage of approximately 4V to 30V. Any voltage lower than that and the board will not be able to power on, but however any voltage significantly above that and the board may suffer permanent damage.

5. What is the maximum temperature value that the LM35 Temperature Sensor Module can read?
a) 100°C
b) 140°C
c) 150°C
d) 130°C
View Answer

Answer: c
Explanation: The maximum temperature that the LM35 Temperature Sensor Module can read is 150°C, above which the module cannot generate sufficient voltage in order to denote a temperature value accurately.
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6. What is the minimum temperature that the LM35 Temperature Sensor Module can read?
a) -11°C
b) -55°C
c) -10°C
d) 0°C
View Answer

Answer: b
Explanation: The minimum temperature that the LM35 Temperature Sensor Module can read is -55°C, below which the module cannot generate sufficiently accurate order of voltage fluctuations to denote a temperature value.

7. If the temperature would be 25°C then what would be the corresponding output on the LM35 Temperature Sensor?
a) 250mV
b) 200mV
c) 25V
d) 250V
View Answer

Answer: a
Explanation: The temperature sensitivity of the LM35 Temperature Sensor Module is 10mV/°C which means that the value of the voltage output will increase linearly with the increase in the surrounding temperature, or in other words it is linearly proportional. Hence if the temperature outside is 25°C then the output would be (10×25)mV or 250mV.
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8. What is the formula for obtaining the temperature value in degrees centigrade from the LM35 Temperature Sensor while using an ADC?
a) °C=ADC/10mV
b) °C=ADC/100mV
c) °C=ADC/1mV
d) °C=ADC/120mV
View Answer

Answer: a
Explanation: The correct formula for converting the voltage reading taken from the ADC into the correct degrees centigrade value of the temperature surrounding the sensor is °C=ADC/10mV. This is because 10mV is the scale factor of the LM35 Temperature Sensor Module.

9. What is the approximate self heating temperature of the LM35 Temperature Sensor Module?
a) 0.08°C
b) 0.91°C
c) 0.11°C
d) 1.23°C
View Answer

Answer: a
Explanation: The correct value of self heating under usual conditions for the LM35 Temperature Sensor Module is approximately 0.08°C. Self heating is the amount of heat that a particular electronic component generates while operating in a circuit due to internal resistances and impedances to the flow of electrons through it.
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10. Does one need to calibrate the LM35 Temperature Sensor Module?
a) Yes
b) No
View Answer

Answer: b
Explanation: There is no need to calibrate the LM35 Temperature Sensor Module since it is already pre-calibrated precisely to the degrees centigrade scale and this is absolute and cannot be changed after the time of manufacture.

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