Free Measurement and Instrumentation MCQs with Answers

• A. to the supply side of the current coil
• B. to the load side of the current coil
• C. in any of the two meters at connection
• D. none of the above

Explanation: In a low-power-factor wattmeter, the pressure coil is connected on the load side of the current coil to reduce the effect of the…

• A. almost zero
• B. low
• C. high
• D. none of the above

Explanation: The moving-coil or pressure-coil circuit of a dynamometer wattmeter must have high resistance so that its current is small and the…

• A. in series with current coil
• B. in parallel with current coil
• C. in series with pressure coil
• D. in parallel with pressure coil

Explanation: The compensating coil is connected in series with the pressure coil so that its magnetic effect compensates for the pressure-coil…

• A. both D.C. and A.C.
• B. D.C. only
• C. A.C. only
• D. any of the above

Explanation: A dynamometer wattmeter uses the interaction of magnetic fields produced by its fixed and moving coils, a principle that works with either…

• A. series
• B. parallel
• C. series-parallel
• D. none of the above

Explanation: A voltmeter is made by connecting a high-value multiplier resistor in series with the meter coil, limiting the current to a safe value.

• A. moving iron instrument
• B. electrostatic instrument
• C. thermocouple instrument
• D. none of the above

Explanation: A thermocouple instrument is suitable for high-frequency current because its thermal action responds to the heating effect and can…

• A. friction compensation
• B. creep compensation
• C. braking torque
• D. none of the above

Explanation: The shading bands on an energy meter adjust the phase and magnitude of the shunt-magnet flux at light load, producing a compensating…

• A. Kelvin's double bridge
• B. Wheat stone bridge
• C. Meggar
• D. None of the above

Explanation: A Megger, or insulation-resistance tester, is designed to measure very high resistances by applying a comparatively high test voltage.

• A. 6 V
• B. 12 V
• C. 40 V
• D. 100 V

Explanation: A Megger contains a hand-driven or electronic high-voltage source, and traditional instruments commonly provide test voltages around 100 V…

• A. short-circuited
• B. all right
• C. faulty

Explanation: A good capacitor initially draws charging current, so the ohmmeter shows low resistance; as the capacitor charges, the current falls and…

• A. a D.C. potentiometer directly
• B. a D.C. potentiometer in conjunction with a standard resistance
• C. a D.C. potentiometer in conjunction with a volt ratio box
• D. none of the above

Explanation: A potentiometer measures voltage directly, so current is found by passing it through a known standard resistance and measuring the voltage…

• A. Small range moving coil voltmeter
• B. D.C. potentiometer
• C. Small range thermocouple voltmeter
• D. None of the above

Explanation: A DC potentiometer is a null-type instrument, so it draws no current from the source at balance and avoids loading errors.

• A. necessary to standardise the potentiometer
• B. not necessary to standardise the potentiometer
• C. necessary to use a volt ratio box in conjunction with the potentiometer
• D. none of the above

Explanation: In resistance measurement by comparing potentiometer balance lengths, the potentiometer constant and working current cancel in the ratio…

• A. battery
• B. permanent magnet D.C. generator
• C. AC. generator
• D. any of the above

Explanation: A conventional hand-driven megger uses a permanent-magnet DC generator to produce its test voltage, avoiding dependence on an external…

• A. D.C. voltmeter
• B. Ammeter and a known resistance
• C. D.C. potentiometer
• D. None of the above

Explanation: A DC potentiometer measures emf under virtually zero current, so there is no internal-resistance voltage drop and the true open-circuit…

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

Explanation: An ohmmeter commonly uses a permanent-magnet moving-coil movement with an internal battery and resistors; the pointer deflection is…

• A. unity
• B. 0.8 lagging
• C. 0.8 leading
• D. zero

Explanation: For two-wattmeter measurement, equal readings require cos(30°−φ) = cos(30°+φ), which gives φ = 0° for a normal balanced load.

• A. An operating torque system
• B. A braking device
• C. Revolution registering device
• D. All of the above

Explanation: A motor meter needs an operating torque to drive its mechanism, a braking device to control speed, and a revolution-registering device to…

• A. an indicating instrument
• B. a recording instrument
• C. an integrating instrument
• D. none of the above

Explanation: A household energy meter accumulates electrical energy over time, usually in kilowatt-hours, rather than merely showing an instantaneous…

• A. secondary instrument
• B. absolute instrument
• C. recording instrument
• D. integrating instrument

Explanation: An ammeter is calibrated against a standard and is used to measure current, so it is a secondary instrument.