Direction: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement – 1 : In the purely resistive element of a series LCR, AC circuit the maximum value of rms current increases with increase in the angular frequency of the applied emf.

Statement – 2 : \(I_{max}=\frac{\varepsilon _{max}}{z},z=\sqrt{R^{2}+\left ( \omega L-\frac{1}{\omega C} \right )^{2}}\) where I_max is the peak current in acycle.

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1

Direction: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement – 1 : A capacitor blocks direct current in the steady state.

Statement – 2 : The capacitive reactance of the capacitor is inversely proportional to frequency f of the source of emf.

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1

A choke is preferred to resistance for limiting current in AC circuit because

choke is cheap
there is now a stage of power
choke is compact in size
choke is good absorber of heat

Solution

In an AC circuit, the coil of high inductance and negligible resistance used to control current, i.e., called the choke coil, the power factor of such a coil is zero.Due to which the power absorbed by the coil is very small. The only loss of energy is due to hysteresis in the iron core, which is much less than the loss of energy in the resistance that can also reduce the current if placed instead of the choke coil.

In a series LCR circuit, resonance occurs at 1 × 10⁵ Hz. At that time, the potential difference across the 100Ω resistor is 40 V while the potential difference across the pure inductor is 30 V. The inductance L of the inductor is equal to :

1.0 × 10 ^–3 H
7.5 × 10 ^–4 H
5.0 × 10 ^–4 H
1.2 × 10 ^–4 H

Solution

The current in resistance R at resonance is

zero
minimum but finite
maximum but finite
infinite

Solution

A coil of self-inductance L is connected in series with a bulb Band an AC source. Brightness of the bulb decreases when

number of turns in the coil is reduced
a capacitance of reactance X_C = X_L is included in the same circuit
an iron rod is inserted in the coil
frequency of the AC source is decreased

Solution

The instantaneous values of alternating current and voltages in a circuit are given as

i = ¹⁄_√2 sin(100πt)A

e = ¹⁄_√2 sin(100πt + π/3)A

The average power in Watt consumed in the circuit is :

¹⁄₄
^√3⁄₄
¹⁄₂
¹⁄₈

Solution

The current (I) in the inductance is varying with time according to the plot shown in figure.

Which one of the following is the correct variation of voltage with time in the coil?

Solution

In an electrical circuit R, L, C and an a.c. voltage source are all connected in series. When L is removed from the circuit,the phase difference between the voltage the current in the circuit is π/3. If instead, C is removed from the circuit, the phase difference is again π/3. The power factor of the circuit is

1/2
1/√2
1
√3/2

Solution

A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency.If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be

4.0 A
8.0 A
²⁰⁄_√13
2.0 A

Solution

The r.m.s. value of potential difference V shown in the figure is

V₀
V₀/√2
V₀/2
V₀/√3

Solution

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

10 mA
100 mA
200 mA
200 mA

Solution

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