Q. In an R-C circuit, the impedance is 40 Ω at a frequency of 100 Hz. At 200 Hz the impedance should be

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Q. An RL series circuit has an impedance of 20 Ω when frequency is 25 Hz. At f= 50 Hz, the impedance will be

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Q. In active filters inductances are divided because they

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Q. Three resistance of 15 Ω each are connected in delta. The resistance of equivalent star will have a value of

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Q. In a varistor the v-i graph is linear.

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Q. The function Z(s) has a pole at infinity if

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Q. An input voltage V(t) = 10 √2 cos (t + 10°) + 10 √3 cos (2t + 10°)V is applied to a series combination of resistance R = 1 kΩ inductance L = 1H. The resulting steady-state current i(t) in ampere is

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Q. A thermal power plant has an efficiency of 0.4. If 0.6 kg of coal is burnt to generate 1 kWh, the calorific value of coal is

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Q. An RC series circuit has R = 20 Ω and XC = 20 Ω. Then Z =

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Q. An inductance having XL = 5 Ω and a capacitance having XC = 5 Ω are connected in parallel across 100 V, 50 Hz supply. The current drawn from source is

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Q. The frame of electric motor is connected to three plates having earthing resistance of 10 Ω, 20 Ω and 30 Ω respectively. The materials of the three plates are copper, aluminium and iron respectively. The percentage of energy dissipated by 10 Ω earthing plate

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Q. A series R-L circuit has R = 1 Ω and L = 1 H. It is excited by a V battery at t = 0. The steady state condition is reached at

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Q. In a purely inductive circuit, the current __________ the voltage by __________ .

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Q. In an RL series circuit the inductance is 1H and current at an instant is 0.6 A. The energy stored in magnetic field is

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Q. In a series ac circuit a voltage of 20 V at 25 Hz causes a current of 0.20 A, while the same voltage at 75 Hz causes a current of 0.12 A. The circuit consists of

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Q. Elements R, L, C are connected in parallel and excited by a dc current I. If iR, iL and iC are the currents through R, L, C respectively then at t = 0

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Q. In a practical voltage source, the terminal voltage

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Q. The function of a choke in a fluorescent lamp is

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Q. A series resonant circuit is fed by a voltage having rms value V. At resonance, the voltage across inductance VL and voltage across capacitance VC are related as

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Q. In a series RLC circuit, R = 2 kΩ, L = 1H and C = µf/400. The resonant frequency is

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