PYQs Based test 17: Electrical & Electronic Measurements

A voltage V₁ is measured 100 times and its average and standard deviation are 100 V and 1.5 V respectively. A second voltage V₂, which is independent of V₁, is measured 200 times and its average and standard deviation are 150 V and 2 V respectively. V₃is computed as: V₃ + V₁ + V₂. Then the standard deviation of V₃ in volts is ________

A 5 A, 110 V electrodynamic type wattmeter has a scale having 110 divisions. Its pressure coil is fed by a voltage of [110 √2 cos314) + √2sin(942t) V and its current coil carries a current of [5√ 2cos(314t + 60) + 2√ 2sin (628t + 90) + √2cos(642t + 90)] A. The needle of the wattmeter will move to

A symmetrical three-phase three-wire RYB system is connected to a balanced delta-connected load. The RMS values of the line current and line-to-line voltage are 10 A and 400 V respectively. The power in the system is measured using the two wattmeter method. The first wattmeter connected between R-line and Y-line reads zero. The reading of the second wattmeter (connected between B-line and Y-line) in watt is _______.

If the deflection of the galvanometer in the bridge circuit shown in the figure is zero, then the value of Rₓ in ohms is _________.

A resistance-meter has five measurement range-settings between 200 Ω and 2 MΩ in multiples of 10. The meter measures resistance of a device by measuring a full-range voltage of 2 V across the device by passing an appropriate constant current for each range-setting. If a device having a resistance value in the range 8 kΩ to 12 kΩ and a maximum power rating of 100 μW is to be measured safely with this meter, the choice for range-setting on the meter for best resolution in measurement, in kΩ, is