Alternating Current
- In an ac circuit an alternating voltage e = 200√2 sin 100 t volts is connected to a capacitor of capacity 1 µF. The r.m.s. value of the current in the circuit is
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Vrms = 200√2 = 200V √2 Irms = Vrms = 200/1 = 2 x 10-2 = 20 mA Xc 100 x 10-6
Correct Option: D
Vrms = 200√2 = 200V √2 Irms = Vrms = 200/1 = 2 x 10-2 = 20 mA Xc 100 x 10-6
- In an a.c circuit the e.m.f. (e) and the current (i) at any instant are given respectively by
e = E0 sin ωt
i = I0 sin (ωt – φ)
The average power in the circuit over one cycle of a.c. is
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The average power in the circuit over one cycle of a.c. is given by
Pav = erms × irms × cosφ= E0 . I0 . cos f = E0 I0 cos f √2 √2 2
Correct Option: C
The average power in the circuit over one cycle of a.c. is given by
Pav = erms × irms × cosφ= E0 . I0 . cos f = E0 I0 cos f √2 √2 2
- The r.m.s. value of potential difference V shown in the figure is
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Correct Option: B
- In an A.C. circuit with voltage V and current I the power dissipated is
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Power dissipated = Erms. Irms = (Erms) (Irms) cos θ
Hence, power dissipated depends upon phase difference.Correct Option: A
Power dissipated = Erms. Irms = (Erms) (Irms) cos θ
Hence, power dissipated depends upon phase difference.
- The instantaneous values of alternating current and voltages in a circuit are given as
i = 1 sin(100πt) amper √2 e = 1 sin(100πt/3) volt √2
The average power in Watts consumed in the circuit is :
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The average power in the circuit where cos φ = power factory
< P > = Vrms × Irms cos φφ = π/3 = phase difference = 180 = 60 3 Vrms = 1/√2 = 1 Volt √2 2 Irms = 1/√2 = 1 Volt √2 2 cos φ = π = 1 3 2 < p > = 1 x 1 x 1 = 1 W 2 2 2 8
Correct Option: D
The average power in the circuit where cos φ = power factory
< P > = Vrms × Irms cos φφ = π/3 = phase difference = 180 = 60 3 Vrms = 1/√2 = 1 Volt √2 2 Irms = 1/√2 = 1 Volt √2 2 cos φ = π = 1 3 2 < p > = 1 x 1 x 1 = 1 W 2 2 2 8