Free Measurement and Instrumentation MCQs with Answers

• A. square law
• B. logarithmic law
• C. uniform law
• D. none of the above

Explanation: A logarithmic scale has decreasing angular spacing for equal increases in the measured quantity, so its graduations become crowded at…

• A. small value of current
• B. large value of current
• C. large value of power
• D. large value of voltage
• E. none of the above

Explanation: Sensitivity is the deflection produced per unit input, so a sensitive galvanometer gives a large deflection even when the current is…

• A. extend voltage range
• B. measure voltage
• C. compare voltage in a box
• D. none of the above

Explanation: A volt box is a precision high-resistance voltage divider connected with a voltmeter.

• A. spherical type
• B. concentric cylindrical type
• C. electrostatic type
• D. multilayer parallel plate type

Explanation: A concentric cylindrical capacitor provides a calculable capacitance based mainly on its dimensions and dielectric, making it suitable as…

• A. induction
• B. moving coil or iron
• C. rectifier
• D. electrostatic

Explanation: Induction instruments operate directly on alternating current and are robust, so they are widely used for AC measurements in power…

• A. Wein bridge
• B. Modified De Santy's bridge
• C. Schering bridge
• D. Any of the above
• E. None of the above

Explanation: The Schering bridge is designed to measure capacitance and dielectric loss, including the properties of high-voltage capacitors and…

• A. known inductance and resistance
• B. known capacitance and resistance
• C. known resistance
• D. known inductance

Explanation: Anderson’s bridge measures an unknown inductance by comparison with a known standard capacitor and known resistances.

• A. improve its ventilation
• B. eliminate creeping at no load
• C. increase its deflecting torque
• D. increase its braking torque

Explanation: Opposite holes reduce the effect of frictional or unequal magnetic forces that can rotate the disc when no load is connected.

• A. Weston frequency meter
• B. reed vibrator frequency meter
• C. heterodoxy frequency meter
• D. electrical resonance frequency meter

Explanation: A heterodyne frequency meter uses a local oscillator and beat-frequency principle, making it suitable for measuring radio frequencies.

• A. electrostatic instrument
• B. thermocouple instrument
• C. moving iron instrument
• D. electrodynamic instrument

Explanation: A moving-iron instrument produces torque mainly proportional to the square of current, so it cannot directly provide the current-voltage…

• A. induction ammeter
• B. permanent magnet type ammeter
• C. electrostatic ammeter
• D. moving iron repulsion type voltmeter

Explanation: An induction ammeter operates only with alternating flux and therefore measures alternating current.

• A. potential transformers
• B. current transformers
• C. both A. and B.
• D. power transformers

Explanation: Instrument transformers include both current transformers, which step down current for measurement and protection, and potential…

• A. get first deflection large
• B. make the system oscillatory
• C. make the system critically damped
• D. get minimum overshoot

Explanation: A ballistic galvanometer measures the first throw produced by a charge, so small damping allows a larger initial deflection and preserves…

• A. platinum
• B. maganin
• C. silver
• D. nichrome

Explanation: Manganin is used for standard resistors because it has high resistivity, a low temperature coefficient and good long-term stability.

• A. accuracy and reproducibility
• B. accuracy, sensitivity and reproducibility
• C. drift and dead zone
• D. static error

Explanation: Accuracy shows closeness to the true value, sensitivity shows response to a small input change, and reproducibility shows agreement under…

• A. moving coil instrument
• B. moving iron instrument
• C. dynamometer instrument
• D. none of the above

Explanation: A Weston frequency meter is a moving-iron instrument in which the relative attraction or repulsion of magnetic elements varies with…

• A. 0.1 Hz
• B. 0.25 Hz
• C. 0.5 Hz
• D. 1.5 Hz

Explanation: In the usual vibrating-reed frequency meter, adjacent reeds are tuned at intervals of 0.5 Hz so that the resonant reed identifies the…

• A. a few volts only
• B. 1 kV
• C. 5 kV
• D. 10 kV

Explanation: The detector in a Schering bridge is connected between points maintained at nearly equal potential, so only a very small voltage appears…

• A. the bridge can always be balanced
• B. the bridge cannot be balanced
• C. the bridge can be balanced if the resistances have some specific values

Explanation: A bridge balances only when the ratios of opposite-arm impedances have equal magnitude and phase.

• A. 10°
• B. 80°
• C. 120°
• D. 170°

Explanation: For a practical capacitor, the current leads the voltage by slightly less than 90°.