In the adjoining figure, the impedance of the circuit will be:
(1) 120 ohm
(2) 50 ohm
(3) 60 ohm
(4) 90 ohm
In a series LCR circuit, which one of the following curves represents the variation of impedance (Z) with frequency (f)?
1. | 2. | ||
3. | 4. |
The variation of the instantaneous current (I) and the instantaneous emf (E) in a circuit are shown in the figure. Which of the following statements is correct?
1. | The voltage lags behind the current by π/2. |
2. | The voltage leads the current by π/2. |
3. | The voltage and the current are in phase. |
4. | The voltage leads the current by π. |
The figure shows the variation of R, XL, and XC with frequency f in a series L, C, R circuit. Then for what frequency point, the circuit is inductive:
(1) A
(2) B
(3) C
(4) All points
An ac source of variable frequency f is connected to an LCR series circuit. Which one of the graphs in the figure represents the variation of the current I in the circuit with frequency f :
(1)
(2)
(3)
(4)
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. What is the power factor of this circuit?
1. 0.4
2. 0.5
3. 0.8
4. 1.0
An inductor 20 mH, a capacitor 50μF, and a resistor 40Ω are connected in series across a source of emf V=10sin340t. The power loss in the AC circuit is:
1. 0.67 W
2. 0.78W
3. 0.89 W
4. 0.46 W
A series R-C circuit is connected to an alternating voltage source. Consider two situations:
1. When the capacitor is air-filled.
2. When the capacitor is mica filled.
Current through the resistor is I and voltage across the capacitor is V then
(1)Va<Vb
(2)Va>Vb
(3)ia>ib
(4)Va=Vb
The instantaneous values of alternating
current and voltages in a circuit are given
as
The average power in Watts consumed in the
circuit is
(a)
(b)
(c)
(d)
In an AC circuit an alternating voltage volt is connected to a capacitor The value of the current in the circuit is
(a) 100 mA
(b) 200 mA
(c) 20 mA
(d) 10 mA