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Correct option is (d) a metal foil

Explanation: Strain is DETECTED in a foil strain GAUGE by making use of a metal foil. The foil makes use of NICKEL, nichrome, CONSTANTAN, isoelastic, and PLATINUM.

The correct choice is (b) CHANGE in length

To explain: A mechanical GAUGE is used to measure the change in length. They make use of GEARS. Mechanical gauges are used for STATIC strain measurements only.

The correct option is (a) resistance, CAPACITANCE and inductance

Easy EXPLANATION: Strain is transferred between the specimen and the gauge element in a strain gauge. ELECTRICAL strain gauges MEASURE the changes OCCURRING in resistance, capacitance and inductance.

Correct ANSWER is (B) 2 forms

Explanation: Strain gauges made out of electrical wires come in two BROAD forms. They are as FOLLOWS:

• Bonded

• Unbonded.

The correct option is (c) 3 types

To elaborate: The bonded electrical wire resistance STRAIN GAUGE is broadly classified into three main types. They are as follows:

• FLAT grid

• Helical grid

• Thin FOIL.

The correct CHOICE is (a) 3 types

For explanation: Strain gauges can be CLASSIFIED into three broad categories based on the principle of operation and CONSTRUCTION. They are mechanical, optical, and ELECTRICAL.

Correct choice is (a) µ = –\(\frac{\Delta d/d}{\Delta l/l}\)

For explanation I would say: POISSON’s ratio is GIVEN by the relation

µ = –\(\frac{\Delta d/d}{\Delta l/l}\)

where,d is the DIAMETER of the cross-section of the WIRE

∆d is the change in the diameter of cross-section of the wire.

The correct OPTION is (d) S = \(\frac{\DELTA R/R}{\Delta l/l}\)

The explanation: GAUGE factor in a strain gauge is given by the relation

S = \(\frac{\Delta R/R}{\Delta l/l}\)

where, S is the gauge factor

R is the gauge wire resistance

∆R is the change in resistance

l is the length of the wire in UNSTRESSED condition

∆l is the change in length of the wire.

The correct choice is (c) bonding

To explain: A strain gauge WORKS properly only if the bonding material USED is durable and keeps the gauge together to the SURFACE of the material that is being TESTED.

Correct CHOICE is (a) nickel and COPPER

Best explanation: Nickel and copper are the most commonly used elements for wire strain GAUGES. They comprise of 45 % of Nickel and 55 % of Copper. They exhibit a HIGH value of SPECIFIC resistance.

The CORRECT choice is (b) 2 types

To explain I would say: Cement can be divided into TWO broad categories. They are as FOLLOWS:

i) SOLVENT setting cement

ii) Chemically REACTING cement.

Correct ANSWER is (d) nickel CHROMIUM alloy

The best I can explain: Nickel chromium alloy is also known as a nichrome alloy. It CONTAINS 80 % of Nickel and 20 % of Chromium. Platinum is used for the temperature compensation of nickel chromium alloys.

Right choice is (b) False

To explain: The gauge is under the same STRAIN as that the specimen under test. As a RESULT the strain gauge is bonded to the specimen.

The correct choice is (a) True

For explanation: The smallest VALUE of strain that can be MEASURED is KNOWN as the sensitivity of the body. The type of strain gauge used dictates the maximum value of strain that can be measured.

Correct choice is (b) False

The EXPLANATION is: Within the elastic LIMITS, the curve of stress vs strain is linear. Strain MEASUREMENTS must be made on the free SURFACE of any BODY. A strain gauge is usually used to measure the magnitude of strain.

The correct answer is (d) force per unit area

For EXPLANATION: STRESS is defined as the RATIO of two quantities as FOLLOWS:

Stress = ^Force⁄Area

The unit of stress is N / m^2.

The correct OPTION is (c) change in length PER unit length

The BEST explanation: STRAIN is defined as the ratio of two QUANTITIES as follows:

Strain = ^∆l⁄l

where,

l is the length

∆l is the change in length.

The correct answer is (b) resistive transducer

For explanation I WOULD say: A strain GAUGE is a resistive transducer. It works on the PRINCIPLE of mechanical displacement into a change in RESISTANCE.

Correct ANSWER is (a) ELECTRICAL signal

Easiest explanation: RESISTIVE transducers are used for transforming the mechanical DISPLACEMENT into electrical signal. Linear displacement is applied to the sliding contact which then converts the change in resistance into voltage or current.

The correct answer is (d) resistive element

The explanation is: A resistive TRANSDUCER in the FORM of a helix is also known as a heliport. They are USED for measuring linear as well as ANGULAR MOTION.

The correct OPTION is (c) high EFFICIENCY

To EXPLAIN I would say: A resistance transducer has a high electrical efficiency. It PROVIDES a sufficient amount of output for further control OPERATIONS.

The correct choice is (a) LINEAR DISPLACEMENT

Best explanation: A Potentiometric RESISTANCE transducer measures linear displacement. It can ALSO be USED for measuring angular displacement.

Right answer is (b) RESISTIVE ELEMENT

The best explanation: A resistance POTENTIOMETER consists of a resistive element. It also has a sliding contact KNOWN as a wiper.

The CORRECT choice is (a) CHANGE in resistivity

Explanation: The change in resistivity of the material of a conductor is used to MEASURE the variation in temperature. Temperature is affected due to change in the resistance which in TURN VARIES the resistivity.

Right choice is (d) RESISTANCE

Easiest explanation: ROTATIONAL potentiometers or translational potentiometers make USE of the change in resistance as a RESULT of the change in length of a CONDUCTOR.

Right OPTION is (a) True

The best I can explain: The passive TRANSDUCERS such as resistor, capacitor and inductor are described through the MEANS of their primary PARAMETERS namely resistance, capacitance and self inductance.

Correct CHOICE is (c) R = ^ρl⁄A

Easy explanation: The resistance of a metallic conductor is given by the relation

R = ^ρl⁄A

where, R is the resistance

l is the length

A is the AREA of cross-section

ρ is the resistivity of MATERIAL of the conductor.

Correct answer is (a) using shock absorbers

The explanation: Transducers can be used EFFECTIVELY in an ENVIRONMENT SUBJECTED to shock and vibrations by MAKING USE of dampers.

The correct CHOICE is (B) 3

Easiest EXPLANATION: There are THREE passive transducers. They are as follows:

Resistor

Capacitor

Inductor.

The correct OPTION is (c) varying electromagnetic FIELDS

Explanation: A transducer should operate under strong electromagnetic fields. Generally transducers with a low value of OUTPUT impedance, high value of output voltage and shorter CABLE LENGTH are not susceptible to such interference.

The correct ANSWER is (d) linear

To explain: Transducer output VARIES linearly with the input quantity that is being measured. A transducer MUST have a linear input vs output characteristic RESPONSE.

The correct choice is (b) minimum loading

To EXPLAIN I would say: A transducer in general should have a minimum AMOUNT of LOAD. Minimum loading effect ensures that the transducer has minimal errors in the measurement of any QUANTITY.

The CORRECT answer is (a) True

The best I can explain: Sensitivity of an ELECTRICAL transducer is DEFINED as the ratio of the electrical OUTPUT to a unit change in the value of a physical QUANTITY such as temperature, pressure, etc.

The CORRECT OPTION is (C) large

For explanation I would say: A transducer has a large range of operation. The operating range is set wide so that it is USEFUL for a wide range of operating FREQUENCIES.

The CORRECT choice is (d) small

For explanation: A transducer generally has a small size and shape. It OCCUPIES MINIMUM volume and has a minimum weight. As a result the system being MEASURED will become COMPACT.

Correct choice is (C) high

The EXPLANATION is: Output of a transducer is usually high so that it can be easily MEASURED and PROCESSED. The transducer output is generally higher than the noise. As a RESULT most of the application makes use of digital outputs.

Right option is (B) be same at all ENVIRONMENT conditions

For explanation: Output of a transducer MUST be the same under various ENVIRONMENTAL conditions when same input is applied to it.

The correct ANSWER is (a) True

To explain I would say: An inverse transducer is used to convert an electrical QUANTITY into a physical quantity. For EXAMPLE, loudspeaker CONVERTS electrical signal into SOUND signal.