This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Thermistor”.
1. Thermistor is a contraction _________
a) thermal resistor
b) laser resistor
c) electric resistor
d) mechanical resistor
Explanation: Thermistor is basically the short form of a thermal resistor. Resistors which depend on temperature are known as thermal resistors.
2. Thermistors have ________
a) positive temperature coefficient
b) negative temperature coefficient
c) zero temperature coefficient
d) infinite temperature coefficient
Explanation: Thermistor generally has a negative temperature coefficient of resistance. With increase in temperature, resistance of a thermistor decreases.
3. Thermistors ________
a) sense large changes in temperature
b) cannot sense any change in temperature
c) sense small changes in temperature
d) have a positive temperature coefficient of resistance
Explanation: Thermistors can sense very small changes in temperature. The negative temperature coefficient of thermistors can be a few percent / degree celcius change in temperature.
4. Thermistor has a resistance of ________
a) 250 ῼ to 500 kῼ
b) 50 ῼ to 10 kῼ
c) 1 ῼ to 1 kῼ
d) 100 ῼ to 100 kῼ
Explanation: Thermistor has a resistance range of 100 ῼ to 100 kῼ. Thermistor consists of a mixture of metallic oxides of manganese, nickel, cobalt, copper, iron and uranium.
5. Thermistors are suited for precision temperature measurements.
Explanation: Thermistors can be used for precision measurement of temperature, controlling g temperature and for temperature compensation due to a very large variation in resistance with temperature.
6. Change in resistance is measured using a ________
a) Anderson’s bridge
b) Wheatstone’s bridge
c) Hay’s bridge
d) Maxwell’s bridge
Explanation: The change in resistance in a thermistor is measured using a Wheatstone’s bridge. It is used for measurement of resistance in the range of -100°C to +200°C.
7. Thermistor material is pressed ________
a) under zero pressure
b) under low pressure
c) under high pressure
d) under low volume
Explanation: A thermistor material is usually pressed under high pressure to form a flat cylindrical shape. Disks and washers are placed in series or in parallel to increase the power dissipation.
8. Thermistor follows which law for small variations ________
a) Charle’s law
d) Ohm’s law
Explanations: For small changes in the values of current, voltage across a thermistor increases. It attains a peak value. Then the voltage across the thermistor decreases. As a result Ohm’s law is followed at small variations of current.
9. At small values of voltage, a thermistor ________
a) reaches peak current slowly
b) reaches peak current immediately
c) does not reaches peak current
d) reaches peak current intermediately
Explanation: For minute variations in voltage, thermistor reaches peak value of current slowly. As the magnitude of voltage is increased, less time is required to attain peak current.
10. Thermistor has a low resistance.
Explanation: Thermistor generally has a very high value of resistance. Cables with shield are required to be used for minimising interference.
Sanfoundry Global Education & Learning Series – Electrical Measurements.
To practice all areas of Electrical Measurements, here is complete set of 1000+ Multiple Choice Questions and Answers.