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
View Answer
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
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Explanation: Thermistor generally has a negative temperature coefficient of resistance. With an 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
View Answer
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
View Answer
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.
a) True
b) False
View Answer
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
View Answer
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
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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
b) KVL
c) KCL
d) Ohm’s law
View Answer
Explanation: 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
View Answer
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 low resistance.
a) True
b) False
View Answer
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.
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