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GATE 2014 EE (EE2) – Question 29

Electrical and Electronic Measurements · Measurement of voltage, current, power, energy and power factor · 1 mark · Numerical answer

The sawtooth shown drives a moving-iron voltmeter. Find its approximate reading (V).

Diagram for GATE 2014 EE (EE2) question 29

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Correct answer: 56 to 59

Explanation

A moving-iron instrument responds approximately to mean-square voltage and is calibrated in rms units. For a linear ramp from0to100over period T,Vrms²=(1/T)∫0^T(100t/T)²dt=10000/3. Hence its reading is **100/√3≈57.735V**,not the50Vaverage.