# Basic Electronics Engineering Questions and Answers – Transducers – Thermistor and Thermocouple – Set 2

This set of Basic Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Transducers – Thermistor and Thermocouple – Set 2”.

1. The time constant of the thermistor is the time for the thermistor to change its resistance by ________ from its initial value.
a) 60%
b) 63%
c) 66%
d) 69%

Explanation: The time constant of the thermistor is the time for the thermistor to change its resistance by 63% from its initial value. It is for achieving the zero-power dissipation.

2. Typical values of time constant range is about ______
a) 1 to 50s
b) 1 to 25s
c) 1 to 100s
d) 1 to 75s

Explanation: Typical values of the time constant range is about 1 to 50s. After this the zero-power dissipation is mostly not seen and the time constant is to achieve the zero-power dissipation.

3. ________ is the power necessary to increase the temperature of thermistor by 10°C.
a) Power dissipation
b) Power factor
c) Dissipation factor
d) Temperature factor

Explanation: The dissipation factor is the necessary to increase the temperature of thermistor by 10°C. The power dissipation means the process in which the electronic device produces heat as unwanted product.

4. Typical values of the dissipation factor is ranges about _________
a) 1-10mW/°C
b) 1-20mW/°C
c) 1-30mW/°C
d) 1-50mW/°C

Explanation: The typical dissipation factor ranges about 1-10mW/°C. The dissipation factor is the requirement to increase the temperature of thermistor by 10°C.

5. Resistance ratio is the ratio of resistance at 25°C to resistance at _______
a) 50°C
b) 100°C
c) 125°C
d) 150°C

Explanation: Resistance ratio is given as the ratio of resistance at 25°C to resistance at 125°C. The time constant, resistance ratio and dissipation constant are the parameters which characterize the thermistor.

6. The thermistor is used to measure flow.
a) True
b) False

Explanation: The thermistor is used to measure the temperature, flow, pressure, liquid level, voltage or power level, vacuum, composition of gases, thermal conductivity and in compensation network.

7. The thermocouple is the junction between two dissimilar metals or semiconductors that generates ________ amount of voltage.
a) High
b) Small
c) Very small
d) Very high

Explanation: The thermocouple is the junction between the two dissimilar metals or semiconductors that generates the small amount of voltage. It is about millivolts.

8. The iron- constantan thermocouple is used to measure the temperature up to ______
a) 700°C
b) 730°C
c) 760°C
d) 790°C

Explanation: The iron- constantan thermocouple is used to measure the temperature about 760°C. The chromel- alumel thermocouple is used to measure the temperature up to 1370°C.

9. A relative small amount of output is obtained, so the it is necessary to amplify for ______
a) Calibration
b) Measurement
c) Calibration and measurement
d) Dissipation

Explanation: The relative small amount of output that is about 50μV/0C is obtained. So, it is necessary to amplify the output for calibration and measurement.

10. The reference junction is maintained at _______ temperature.
a) 100°C
b) 50°C
c) 150°C
d) Fixed

Explanation: The reference junction is maintained at fixed temperature. Usually, it is maintained at 0°C and the output depends on the temperature at sensing junction.

Sanfoundry Global Education & Learning Series – Basic Electronics Engineering.

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