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The value of series resistance to be used to extend ( 0- 200) V range voltmeter having $2000\Omega /V$ sensitivity to be extended to ( 0-2000) V range.

The full-sclae deflecting torque of a 10 ampere moving iron ammeter is $4\times {10}^{-5}N-m.$ The rate of changes of self inductance of instrument at full scale is

1. 200

A wire potentiometer of length 11 m and resistance $1\Omega /m$ balances a standard cell voltage of 1.018 V at a length of 10 m 18 cm. If the voltage of the battery supplying the current through the potentiometer is 2.0 V, then the value of the series resistance connected to the potentiometer is

An oscilloscope is powered from $230V$ mains having a nominal frequency of nearly $50Hz.$ The triggering mode of the oscilloscope is set to LINE. A square wave from a function generator is fed to the Y input and a stable display (properly triggered) is obtained when the frequency of the function generator is $297Hz.$ The actual frequency of the power supply is

A DC voltmeter has a sensitivity of $1000\Omega /volt.$ When it measures half of full scale in 100 V range, the current though the voltmeter is

Three moving iron type voltmeters are connected as shown below. Voltmeter readings are $V,V_1$ and $V_2$ as indicated . The correct relation among the voltmeter readings is

The op-amp based circuit of a half wave rectifier electronic voltmeter shown below uses a PMMC ammeter with a full scale deflection (FSD) current of 1 mA and a coil resistance of $1k\Omega .$ The value of R that gives FSD for a sinusoidal input voltage of 100 mV (RMS) is

Two ammeters $A_1$ and $A_2$ measure the same current and provide readings $I_{1}and{I}_2,$ respectively. The ammeter errors can be characterized as independent zero mean Gaussian random variable of standard deviations ${\sigma }_{1}and{\sigma }_2,$ respectively. The value of the current is computed as:



$I=\mu I_1+(1-\mu )I_2$



The value of $\mu$ which gives the lowest standard deviation of I is

For the circuit in the figure, the voltage and current expressions are:

$v\left(t\right)=E_{1}sin\left(\omega t\right)+E_{3}sin\left(3\omega t\right)$

and $i\left(t\right)=I_{1}sin(\omega t-{\varphi }_1)+I_{3}sin(3\omega t-{\varphi }_3)+I_{5}sin\left(5\omega t\right)$

The average power measured by the Wattmeter is

The load shown in the figure is supplied by a 400 V (line-to-line), 3-phase source (RYB sequence). The load is balanced and inductive, drawing 3464 VA. When the switch S is in position N, the three watt-meters $W_1,W_{2}and{W}_3$ read 577.35 W each. If the switch is moved to position Y, the readings of the wattmeters in watts will be:

1. 100

The x and y sensitivities of an analog oscilloscope are set as 2 ms/cm and 1 V/cm respectivley. The trigger is set at 0 V with negative slope. An input of $2cos(100\pi t+{30}^o)V$ is fed to the y input of the oscilloscope. The wave form seen on the oscilloscope will be

A $\text{20VA, 100/2 A}$ current transformer has an iron loss of 0.5W and magnetizing current of 1.2A. If the rated output is supplied to a motor having a ratio of resistance to reactance of 4, the value of phase angle (in degree) will be

1. 2.18

A temperature sensor having a range of 0-100°C has a worst case accuracy specification of $\pm 1.0\%$ of true value or $\pm 0.3\%$ of full scale, whichever is higher. The sensitivity of the sensor is experimentally obtained by taking its readings at true temperatures 25°C and 75°C. The maximum error in sensitivity, expressed as percentage of its ideal value is

The Maxwell's bridge shown in the figue is at balance. The parameters of the inductive coil are

Three DC currents, $I_1,I_{2}and{I}_3$ meet at a node with $I_1$ entering, $I_{2}and{I}_3$ leaving the node. $I_{1}and{I}_2$ are measured as 100 mA and 99 mA with $\pm 1$% accuracy. Then the value $I_3$ and the accuracy of $I_3$ are

The linear sweep for the time base in an oscilloscope has deviation from its nominal waveform. The nominal (dashed line) and actual (solid line) sweep waveforms are shown in the following figure.



A $5V$ p-p sine wave with a frequency of $1kHz$ will be measured on the oscilloscope as a sine wave with

For a given frequency, the deflecting torque in an induction type ammeter is directly proportional to

Two wattmeters are connected to measure power in a 3-phase network. The two readings are 2000 watts and 1000 watts respectively. If another wattmeter to be connected such that its current coil is in one phase and the potential coil is across the other two phase terminals. Then the reading of wattmeter is _______VAR.

For the network shown in the figure, the voltage across terminal AB is measured by a voltmeter. The sensitivity of voltmeter is $2k\Omega /volt$. Which of the following statement is true?

A rectifier type PMMC voltmeter has a sensitivity of $20k\Omega /V.$ A reading of 4.5 V is obtained when measuring a voltage source with an internal resistance on it's 5 V scale. When the scale is changed to 10 V full scale, a reading of 6 V is obtained. The value of the voltage and it's internal resistance R are

The voltage phasor of a circuit is $10\angle {15}^{\circ }V$ and the current phasor is $2\angle -{45}^{\circ }A$. The active and the reactive powers in the circuit are

1. 10

The measured system shown in the figure uses thee sub-system in cascade whose gains are specified as $G_1,G_{2}and1/G_3$. The relative small errors associated with each respective subsystem $G_1,G_{2}and{G}_3$ are ${\epsilon }_1,{\epsilon }_{2}and{\epsilon }_3$. The error associated with the output is:

1. 0.1

The line to line input voltage to the 3-phase 50 Hz, AC circuit shown in figure is 100 V rms. Assuming that the phase sequence is RYB the wattmeter would read.

1. -4.5

Two $100\mu A$ full sale PMMC meters are employed to construct a 10 V and a 100 V full scale voltmeter.These meters will have figure of merits (sensitivities)as