Electrical & Electronics Measurements Objective Questions – Set 3

A sampling wattmeter is used to measure the average power of a load. The peak to peak voltage of a square wave is 10 V and the current is triangular wave of 5 Amp P-P as shown in the figure. The period is 20 ms. The reading in W will be

A DC A-h meter is rated for 15 A, 250 V. The meter constant is 14.4 A-sec/rev. The meter constant at rated voltage may be expressed as

A single phase load is connected between R and Y terminals of a 415 V, symmetrical, 3-phase, 4 wire system with phase sequence RYB. A wattmeter is connected in the system as shown in figure. The power factor of the load is 0.8 lagging. The wattmeter will read

In DC potentiometer measurments, a second reading is often taken after reversing the polarities of the DC supply and the unknown voltage and the average of the two reading is taken. This is with a view of eliminate the effects of

A sinusoidal signal waveform, when observed on an oscilloscope, has a peak to peak amplitude of 6 cm. If the vertical sensitivity setting is 5 v/cm, then rms value of the voltage will be

What is the standard unit for length ?

In the bridge given in the figure, the reasing of the high impedance voltmeter is

A 50 Hz bar primary CT has a secondary with 500 turns. The secondary supplies 5 A current into a purely resistive burden of 1Ω. The magnetizing ampere-turn is 200. The phase angle between the primary and secondary current is

Which of the quantity consists of unit as newton-second?

The items in Group-I represent the various types of weasurement to be made with a reasonable accuracy using a suitable bridge. The items in Group-II represent the various bridges available for this purpose. Select the correct choice of the item in Group-II for the corresponding item in Group-I from the following Group I: P.Resistance in mili-ohm range. Q. Low values of capacitance. R. Comparison of resistance which are nearly equal. S. Inductance of a coil with a large time constant. Group-II: 1. Wheatstone bridge. 2. Kelvine double bridge. 3. Scherings bridge. 4. Weins bridge 5. Hays bridge 6. Carey-foster bridge

A Manganin swap resistance is connected in series with a moving coil ammeter consisting of a milli ammeter and a suitable shunt in order to

The meter constant of a single phase 240 V induction watthour meter is 400 revolutions per KWh. The speed of the meter disc for a current of 10 Amperes of 0.8 p.f lagging will be

Which of following statement are correct in case of power factor meter?

The effect of load resistance is important in measurement of

Potentiometer methode of DC voltage measurement is more accurate than direct measurement using a voltmeter because

The time/div and voltage axes of an oscilloscope have been creased. A student connects a 1 KHz, 5 V P-P square wave calibrition pulse to channel-1 of the scope and observes the screen to be as shown in the upper trace of figure. An unknown signal is connected to channel-2 (lower trace) of the scope. If the time/div and V/div on both channels are the same, the amplitude (P-P) and period of the unknown signal are respectively

A Lissajous pattern on an oscilloscope has 5 horinzontal tangencies and 2 vertical tangencies. The frequency of horizontal input is 100 Hz. The frequency of the vertical will be

A slide wire potentiometer has 10 wires at 1 m each. With the help of a standard voltage source of 1.018 V it is standarddised by keeping the jockey at 101.8 cm. If the resistance of the potentiometer wires is 1000 ohm, then the value of the working current will be

Which of the quantity consists of unit as Pascal ?

The measurment of very low and very high frequencies is invariably done using a frequency counter in which one of the following?

A bridge circuit is shown in the figure below. Which one of the sentence given below is most suitable for balancing the bridge?

The errors mainly caused by human mistakes are

Which of following are needed both for protection and metering?

A moving coil of a meter has 100 turns, and a length and depth of 10 mm and 20 mm respectively. It is postioned in a uniform radial flux density of 200 mT. The coil carries a current of 50 mA. The torque on the coil is

Consider the following statement - 1. The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the current coil. 2. The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the voltage coil circuit.

Assertion (A): A hot wire ammeter has a cramped scale. Reason (R): The heat is proportional to square of current.

A voltmeter using thermocouple measures

What is the name of physical quantities which are independent of each other?

Piezoelectronic accelerometer

If an inductance L is connected in one arm of bridge and resistance R₁, R₂, R₃ in other three arms