A transformer of 100% efficiency has 200 turns in the primary coil and 40000 turns in secondary coil. It is connected to a 220 V main supply and secondary feeds to a 100 kΩ resistance. […]
In an electrical circuit R,L,C and an AC voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is […]
If in a L-R series circuit the power factor is 1/2 and R=100Ω, then the value of L is, when AC mains is used
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(a) πH (b) √3/π H (c) π/√3 H (d) […]
The self-inductance of a choke coil is 10 mH. When it is connected with a 10 V DC source, then the loss of power is 20 W. When its is connected with 10 V AC […]
The power factor of an AC circuit having resistance R and inductance L connected in series to an AC source of angular frequency ω is
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(a) zero (b) ωL/R (c) R/√R²+ω²L² (d) R/ωL
An air core coil and an electric bulb are connected in series with an AC source. If an iron rod is put in the coil, then the intensity of light of the bulb will
For a series L-C-R circuit, the rms values of voltage across various components are Vʟ=90 V, Vᴄ=60V and Vʀ=40 V. The rms value of the voltage applied to the circuit is
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(a) […]
Alternating current is transmitted to distant places at
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(a) Low voltage and high current (b) Low voltage and low current (c) High voltage and high current (d) High voltage and low current
The primary of a transformer when connected to a dc battery of 10 volt draws a current of 1mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The […]
If an A.C. mains supply is given to be 220 V, what would be the average e.m.f. during a positive half cycle?
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(a) 256 V (b) 512 V (c) 386 V (d) 198 […]
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