# Linear Integrated Circuit Questions and Answers – Instrumentation Amplifier – 3

This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Instrumentation Amplifier – 3”.

1. Strain gage are used to monitor change in
a) Pressure
b) Torque
c) Displacement
d) All of the mentioned

Explanation: A strain gage may be used to monitor change in applied pressure, torque and displacement by measuring the corresponding change in the gage resistance.

2. Which type of resistive transducer is most commonly used?
a) Thermistor
b) Photoconductive cell
c) Strain gage
d) All of the mentioned

Explanation: Thermistors are most commonly used because they are relatively easy to mount.

3. What is the unit of strain gage?
a) Ω/oC
b) Lux
c) Newton / meter2
d) Volts

Explanation: Strain gage changes resistance when an external stress is applied. Therefore, the stress is defined as force/unit area i.e. Newton / meter^2.

4. Which type of strain gage has better resolution?
a) Semiconductor strain gage
b) Wire strain gage
c) Wire and Semiconductor strain gage
d) None of the mentioned

Explanation: Semiconductor strain gage are much more sensitive than wire type and so, it provide better accuracy and resolution.

5. How a differential instrumentation amplifier using transducer bridge can be used as a temperature controller?
a) Increase room temperature
b) Replaces calibrated meter with relay
c) Change the bridge resistance
d) Replace thermistor by light intensity meter

Explanation: A simple and inexpensive temperature controller can be constructed by replacing a meter with a relay in the circuit. So, the output of the differential instrumentation amplifier drives a relay output of the differential instrumentation amplifier drives a relay that controls the current on the heat generating circuit.

6. The strain gage elements in the analog weight scale are mounted on a
a) Base of weight platform
b) Hanging weight platform
d) Varying weight platform

Explanation: The strain gage elements are mounted in the base of the weight platform. So, that whenever external force or weight is applied to the platform, one pair of element in the opposite arm of bridge elongates, whereas the other pair in opposite arm compresses.

7. What will be the resultant circuit, when the thermistor in the bridge transducer is replaced by a strain gage?
a) Differential input and differential output amplifier
b) Light intensity
c) Analog weight scale
d) None of the mentioned

Explanation: By connecting a strain gage in the transducer bridge, the differential instrumentation amplifier circuit can be converted in a simple and inexpensive analog weight scale.

8.

RT1, RT2, RT3, RT4 are unstrained gage resistance. If the resistance change in each gage is 0.3Ω. Choose the correct option?
1. RT1 and RT3 increases by 0.3Ω
2. RT2 and RT4 decreases by 0.3Ω
3. RT1 and RT3 increases by 0.3Ω
4. RT2 and RT4 decreases by 0.3Ω
a) 3 and 4
b) 1 and 2
c) 1 and 4
d) 2 and 3

Explanation: When external weight is applied to the platform. One pair of element elongate and the other pair compresses. Therefore, RT1 and RT3 is △R and the increase in RT2 and RT4 is also by △R.

Sanfoundry Global Education & Learning Series – Linear Integrated Circuits.