Alternating Current

174 questions · Physics · JEE Main

Alternating Current

174 questions · Physics · JEE Main

An electric bulb rated as $100 W - 220 V$ is connected to an ac source of rms voltage 220 V. The peak value of current through the bulb is :2025 · 3 Apr · Shift 2 · Q69 · MCQ
An alternating current is represented by the equation, $i = 1002 sin (100 π t)$ ampere. The RMS value of current and the frequency of the given alternating current are2025 · 4 Apr · Shift 1 · Q56 · MCQ
An inductor of self inductance 1 H is connected in series with a resistor of $100 π$ ohm and an ac supply of $100 π$ volt, 50 Hz . Maximum current flowing in the circuit is A.2025 · 4 Apr · Shift 2 · Q72 · Numerical
An ac current is represented as $i = 52 + 10 cos (650 π t + \frac{π}{6}) A m p$ The r.m.s value of the current is2025 · 7 Apr · Shift 1 · Q55 · MCQ
For ac circuit shown in figure, $R = 100 k Ω$ and $C = 100 pF$ and the phase difference between $V_{in}$ and $(V_{B} - V_{A})$ is $9 0^{\circ}$ … Includes diagram2025 · 7 Apr · Shift 1 · Q73 · Numerical
An inductor of reactance $100Ω$ , a capacitor of reactance $50Ω$ , and a resistor of resistance $50Ω$ are connected in series with an AC source of $10 V, 50 Hz$ . Average power dissipated by the circuit…2025 · 7 Apr · Shift 2 · Q73 · Numerical
A series LCR circuit is connected to an alternating source of emf E. The current amplitude at resonant frequency is $I_{0}$ . If the value of resistance R becomes twice of its initial value then amplitude of current at resonance will be2025 · 22 Jan · Shift 2 · Q62 · MCQ
In a series LCR circuit, a resistor of $300Ω$ , a capacitor of 25 nF and an inductor of 100 mH are used. For maximum current in the circuit, the angular frequency of the ac source is $\times 1 0^{4}$ radians $s^{- 1}$ …2025 · 23 Jan · Shift 2 · Q72 · Numerical
An alternating current is given by $I = I_{A} sin ω t + I_{B} cos ω t$ . The r.m.s current will be2025 · 24 Jan · Shift 1 · Q69 · MCQ
A parallel plate capacitor has a capacitance $C = 200 pF$ . It is connected to $230 V$ ac supply with an angular frequency $300 rad / s$ . The rms value of conduction current in the circuit and…2024 · 1 Feb · Shift 1 · Q71 · MCQ
In series LCR circuit, the capacitance is changed from $C$ to $4 C$ . To keep the resonance frequency unchanged, the new inductance should be:2024 · 1 Feb · Shift 1 · Q77 · MCQ
In an ac circuit, the instantaneous current is zero, when the instantaneous voltage is maximum. In this case, the source may be connected to : A. pure inductor. B. pure capacitor. C. pure resistor. D. combination of an inductor and…2024 · 4 Apr · Shift 1 · Q67 · MCQ
A alternating current at any instant is given by $i = [6 + 56 sin (100 π t + π /3)]$ A. The $r m s$ value of the current is A.2024 · 4 Apr · Shift 1 · Q88 · Numerical
Match List I with List II Choose the correct answer from the options given below: Includes table Includes diagram2024 · 4 Apr · Shift 2 · Q63 · MCQ
An alternating voltage of amplitude $40 V$ and frequency $4 kHz$ is applied directly across the capacitor of $12 μ F$ . The maximum displacement current between the plates of the capacitor is nearly :2024 · 5 Apr · Shift 1 · Q63 · MCQ
An ac source is connected in given series LCR circuit. The rms potential difference across the capacitor of $20 μ F$ is V. Includes diagram2024 · 5 Apr · Shift 1 · Q87 · Numerical
A series LCR circuit is subjected to an ac signal of $200 V, 50 Hz$ . If the voltage across the inductor $(L = 10 mH)$ is $31.4 V$ , then the current in this circuit is…2024 · 5 Apr · Shift 2 · Q68 · MCQ
Given below are two statements : Statement I : In an LCR series circuit, current is maximum at resonance. Statement II : Current in a purely resistive circuit can never be less than that in a series LCR circuit when connected to same…2024 · 6 Apr · Shift 1 · Q74 · MCQ
When a $d c$ voltage of $100 V$ is applied to an inductor, a $d c$ current of $5 A$ flows through it. When an ac voltage of $200 V$ peak value is connected to inductor, its inductive reactance is found to be $203 Ω$ …2024 · 6 Apr · Shift 1 · Q89 · Numerical
For a given series LCR circuit it is found that maximum current is drawn when value of variable capacitance is $2.5 nF$ . If resistance of $200Ω$ and $100 mH$ inductor is being used in the given circuit. The…2024 · 6 Apr · Shift 2 · Q80 · Numerical
A LCR circuit is at resonance for a capacitor C, inductance L and resistance R. Now the value of resistance is halved keeping all other parameters same. The current amplitude at resonance will be now:2024 · 8 Apr · Shift 1 · Q73 · MCQ
A coil of negligible resistance is connected in series with $90Ω$ resistor across $120 V, 60 Hz$ supply. A voltmeter reads $36 V$ across resistance. Inductance of the coil is :2024 · 8 Apr · Shift 2 · Q79 · MCQ
An alternating emf $E = 1102 sin 100 t$ volt is applied to a capacitor of $2 μ F$ , the rms value of current in the circuit is $mA$ .2024 · 8 Apr · Shift 2 · Q81 · Numerical
A bulb and a capacitor are connected in series across an ac supply. A dielectric is then placed between the plates of the capacitor. The glow of the bulb :2024 · 9 Apr · Shift 1 · Q79 · MCQ
When a coil is connected across a $20 V$ dc supply, it draws a current of $5 A$ . When it is connected across $20 V, 50 Hz$ ac supply, it draws a current of $4 A$ . The self inductance of the…2024 · 9 Apr · Shift 1 · Q89 · Numerical
A capacitor of reactance $43 Ω$ and a resistor of resistance $4Ω$ are connected in series with an ac source of peak value $82 V$ . The power dissipation in the circuit is W.2024 · 9 Apr · Shift 2 · Q90 · Numerical
Primary side of a transformer is connected to $230 V, 50 Hz$ supply. Turns ratio of primary to secondary winding is $10 : 1$ . Load resistance connected to secondary side is $46Ω$ . The power consumed in it is :2024 · 27 Jan · Shift 2 · Q64 · MCQ
A series LCR circuit with $L = \frac{100}{π} mH, C = \frac{1 0 ^{- 3}}{π} F$ and $R = 10Ω$ , is connected across an ac source of $220 V, 50 Hz$ supply. The power factor of…2024 · 27 Jan · Shift 2 · Q82 · Numerical
A capacitor of capacitance $100 μ F$ is charged to a potential of $12 V$ and connected to a $6.4 mH$ inductor to produce oscillations. The maximum current in the circuit would be :2024 · 29 Jan · Shift 1 · Q65 · MCQ
In an a.c. circuit, voltage and current are given by: $V = 100 sin (100 t) V$ and $I = 100 sin (100 t + \frac{π}{3}) mA$ respectively. The average power dissipated in one cycle is:2024 · 29 Jan · Shift 2 · Q73 · MCQ
Primary coil of a transformer is connected to $220 V$ ac. Primary and secondary turns of the transforms are 100 and 10 respectively. Secondary coil of transformer is connected to two series resistances shown in figure. The output… Includes diagram2024 · 30 Jan · Shift 1 · Q63 · MCQ
A series L.R circuit connected with an ac source $E = (25 sin 1000 t) V$ has a power factor of $\frac{1}{2}$ . If the source of emf is changed to $E = (20 sin 2000 t) V$ , the new power factor of the circuit…2024 · 30 Jan · Shift 1 · Q66 · MCQ
An alternating voltage $V (t) = 220 sin 100 π t$ volt is applied to a purely resistive load of $50Ω$ . The time taken for the current to rise from half of the peak value to the peak value is:2024 · 30 Jan · Shift 2 · Q64 · MCQ
A power transmission line feeds input power at $2.3 kV$ to a step down transformer with its primary winding having 3000 turns. The output power is delivered at $230 V$ by the transformer. The current in the primary of…2024 · 30 Jan · Shift 2 · Q82 · Numerical
An AC voltage $V = 20 sin 200 π t$ is applied to a series LCR circuit which drives a current $I = 10 sin (200 π t + \frac{π}{3})$ . The average power dissipated is:2024 · 31 Jan · Shift 2 · Q78 · MCQ
Match List - I with List - II : Choose the correct answer from the options given below : Includes table2023 · 1 Feb · Shift 1 · Q46 · MCQ
A series LCR circuit is connected to an ac source of $220 V, 50 Hz$ . The circuit contain a resistance $R = 100 Ω$ and an inductor of inductive reactance $X_{L} = 79.6 Ω$ . The…2023 · 1 Feb · Shift 1 · Q68 · Numerical
A square shaped coil of area $70 cm^{2}$ having 600 turns rotates in a magnetic field of $0.4 wbm^{- 2}$ , about an axis which is parallel to one of the side of the coil and perpendicular to the direction of field. If the…2023 · 1 Feb · Shift 2 · Q65 · Numerical
An ideal transformer with purely resistive load operates at $12 kV$ on the primary side. It supplies electrical energy to a number of nearby houses at $120 V$ . The average rate of energy consumption in the houses served…2023 · 6 Apr · Shift 1 · Q70 · Numerical
A capacitor of capacitance $150.0 μ F$ is connected to an alternating source of emf given by $E = 36 sin (120 π t) V$ . The maximum value of current in the circuit is approximately equal to :2023 · 6 Apr · Shift 2 · Q52 · MCQ
An oscillating LC circuit consists of a $75 mH$ inductor and a $1.2 μ F$ capacitor. If the maximum charge to the capacitor is $2.7 μ C$ . The maximum current in the circuit will be $mA$ …2023 · 8 Apr · Shift 1 · Q74 · Numerical
Given below are two statements: Statement I : Maximum power is dissipated in a circuit containing an inductor, a capacitor and a resistor connected in series with an AC source, when resonance occurs Statement II : Maximum power is…2023 · 10 Apr · Shift 1 · Q61 · MCQ
As per the given graph, choose the correct representation for curve $A$ and curve B. Where $X_{C} =$ reactance of pure capacitive circuit connected with A.C. source $X_{L} =$ reactance of pure… Includes diagram2023 · 11 Apr · Shift 1 · Q65 · MCQ
A coil has an inductance of $2 H$ and resistance of $4 Ω$ . A $10 V$ is applied across the coil. The energy stored in the magnetic field after the current has built up to its equilibrium value will be …2023 · 11 Apr · Shift 2 · Q69 · Numerical
Given below are two statements: Statement I : When the frequency of an a.c source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR…2023 · 12 Apr · Shift 1 · Q59 · MCQ
In the given figure, an inductor and a resistor are connected in series with a battery of emf E volt. $\frac{E ^{a}}{2 b} J / s$ represents the maximum rate at which the energy is stored in the magnetic field (inductor). The… Includes diagram2023 · 13 Apr · Shift 1 · Q68 · Numerical
Given below are two statements: Statement I : An AC circuit undergoes electrical resonance if it contains either a capacitor or an inductor. Statement II : An AC circuit containing a pure capacitor or a pure inductor consumes high power…2023 · 13 Apr · Shift 2 · Q57 · MCQ
In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes $x$ times its initial resonant frequency $ω_{0}$ . The value of $x$ is :2023 · 25 Jan · Shift 1 · Q61 · MCQ
An LCR series circuit of capacitance 62.5 nF and resistance of 50 $Ω$ , is connected to an A.C. source of frequency 2.0 kHz. For maximum value of amplitude of current in circuit, the value of inductance is …2023 · 25 Jan · Shift 1 · Q70 · Numerical
A series LCR circuit is connected to an AC source of 220 V, 50 Hz. The circuit contains a resistance R = 80 $Ω$ , an inductor of inductive reactance $X_{L} = 70Ω$ , and a capacitor of capacitive reactance $X_{C} = 130Ω$ …2023 · 25 Jan · Shift 2 · Q70 · Numerical
For the given figures, choose the correct options : Includes diagram2023 · 29 Jan · Shift 2 · Q54 · MCQ
An inductor of inductance 2 $μ H$ is connected in series with a resistance, a variable capacitor and an AC source of frequency 7 kHz. The value of capacitance for which maximum current is drawn into the circuit $\frac{1}{x} F$ …2023 · 29 Jan · Shift 2 · Q64 · Numerical
In a series LR circuit with $X_{L} = R$ , power factor P1. If a capacitor of capacitance C with $X_{C} = X_{L}$ is added to the circuit the power factor becomes P2. The ratio of P1 to P2 will be :2023 · 30 Jan · Shift 1 · Q58 · MCQ
In the given circuit, rms value of current $(I_{rms})$ through the resistor $R$ is: Includes diagram2023 · 30 Jan · Shift 2 · Q52 · MCQ
In an ac generator, a rectangular coil of 100 turns each having area $14 \times 1 0^{- 2} m^{2}$ is rotated at $360 rev / min$ about an axis perpendicular to a uniform magnetic field of magnitude $3.0…2023 · 30 Jan · Shift 2 · Q62 · Numerical
If $R, X_{L}$ , and $X_{C}$ represent resistance, inductive reactance and capacitive reactance. Then which of the following is dimensionless :2023 · 31 Jan · Shift 1 · Q58 · MCQ
An inductor of $0.5 mH$ , a capacitor of $20 μ F$ and resistance of $20 Ω$ are connected in series with a $220 V$ ac source. If the current is in phase with the emf, the amplitude of current of the…2023 · 31 Jan · Shift 1 · Q74 · Numerical
An alternating voltage source $V = 260 sin (628 t$ ) is connected across a pure inductor of $5 mH$ Inductive reactance in the circuit is :2023 · 31 Jan · Shift 2 · Q60 · MCQ
A series $LCR$ circuit consists of $R = 80Ω, X_{L} = 100Ω$ , and $X_{C} = 40Ω$ . The input voltage is 2500 $cos (100 π t) V$ . The amplitude of current, in…2023 · 31 Jan · Shift 2 · Q64 · Numerical
A resistance of 40 $Ω$ is connected to a source of alternating current rated 220 V, 50 Hz. Find the time taken by the current to change from its maximum value to the rms value :2022 · 24 Jun · Shift 1 · Q54 · MCQ
As shown in the figure an inductor of inductance 200 mH is connected to an AC source of emf 220 V and frequency 50 Hz. The instantaneous voltage of the source is 0 V when the peak value of current is $\frac{a}{π}$ A. The value… Includes diagram2022 · 24 Jun · Shift 1 · Q64 · Numerical
Given below are two statements : Statement I : The reactance of an ac circuit is zero. It is possible that the circuit contains a capacitor and an inductor. Statement II : In ac circuit, the average power delivered by the source never…2022 · 24 Jun · Shift 2 · Q54 · MCQ
To increase the resonant frequency in series LCR circuit,2022 · 25 Jul · Shift 1 · Q52 · MCQ
When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works on :2022 · 25 Jul · Shift 2 · Q54 · MCQ
Match List-I with List-II. Choose the correct answer from the options given below : Includes table2022 · 25 Jun · Shift 1 · Q52 · MCQ
If wattless current flows in the AC circuit, then the circuit is :2022 · 25 Jun · Shift 1 · Q54 · MCQ
A sinusoidal voltage V(t) = 210 sin 3000 t volt is applied to a series LCR circuit in which L = 10 mH, C = 25 $μ$ F and R = 100 $Ω$ . The phase difference ( $Φ$ ) between the applied voltage and resultant current will be :2022 · 25 Jun · Shift 2 · Q57 · MCQ
In a series LCR circuit, the inductance, capacitance and resistance are L = 100 mH, C = 100 $μ$ F and R = 10 $Ω$ respectively. They are connected to an AC source of voltage 220 V and frequency of 50 Hz. The approximate value of… Includes diagram2022 · 25 Jun · Shift 2 · Q72 · Numerical
In a series $L R$ circuit $X_{L} = R$ and power factor of the circuit is $P_{1}$ . When capacitor with capacitance $C$ such that $X_{L} = X_{C}$ is put in series, the power factor becomes $P_{2}$ . The ratio $\frac{P _{1}}{P _{2}}$ is:2022 · 26 Jul · Shift 1 · Q50 · MCQ
The effective current I in the given circuit at very high frequencies will be A. Includes diagram2022 · 26 Jul · Shift 1 · Q69 · Numerical
A 110 V, 50 Hz, AC source is connected in the circuit (as shown in figure). The current through the resistance 55 $Ω$ , at resonance in the circuit, will be A. Includes diagram2022 · 26 Jun · Shift 1 · Q67 · Numerical
A direct current of $4 A$ and an alternating current of peak value $4 A$ flow through resistance of $3 Ω$ and $2 Ω$ respectively. The ratio of heat produced in the two resistances in same interval of time…2022 · 27 Jul · Shift 1 · Q58 · MCQ
To light, a $50 W, 100 V$ lamp is connected, in series with a capacitor of capacitance $\frac{50}{π x} μ F$ , with $200 V, 50 Hz AC$ source. The value of $x$ will be …2022 · 27 Jul · Shift 1 · Q66 · Numerical
A series LCR circuit has $L = 0.01 H, R = 10 Ω$ and $C = 1 μ F$ and it is connected to ac voltage of amplitude $(V_{m}) 50 V$ . At frequency $60…2022 · 27 Jul · Shift 2 · Q52 · MCQ
The current flowing through an ac circuit is given by I = 5 sin(120 $π$ t)A How long will the current take to reach the peak value starting from zero?2022 · 27 Jun · Shift 1 · Q52 · MCQ
A 220 V, 50 Hz AC source is connected to a 25 V, 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be . Includes diagram2022 · 27 Jun · Shift 1 · Q61 · Numerical
If L, C and R are the self inductance, capacitance and resistance respectively, which of the following does not have the dimension of time?2022 · 27 Jun · Shift 2 · Q58 · MCQ
The equation of current in a purely inductive circuit is $5 sin (49 π t - 3 0^{\circ})$ . If the inductance is $30 mH$ then the equation for the voltage across the inductor, will be : ${$ Let $π = \frac{22}{7}}$ …2022 · 28 Jul · Shift 1 · Q59 · MCQ
The frequencies at which the current amplitude in an LCR series circuit becomes $\frac{1}{2}$ times its maximum value, are $212 rad s^{- 1}$ and $232 rad s^{- 1}$ . The value of resistance in…2022 · 28 Jul · Shift 1 · Q66 · Numerical
A transformer operating at primary voltage $8 kV$ and secondary voltage $160 V$ serves a load of $80 kW$ . Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the…2022 · 28 Jul · Shift 2 · Q53 · MCQ
An AC source is connected to an inductance of 100 mH, a capacitance of 100 $μ$ F and a resistance of 120 $Ω$ as shown in figure. The time in which the resistance having a thermal capacity 2 J/ $^{\circ}$ C will get heated by 16… Includes diagram2022 · 28 Jun · Shift 1 · Q63 · Numerical
A telegraph line of length 100 km has a capacity of 0.01 $μ$ F/km and it carries an alternating current at 0.5 kilo cycle per second. If minimum impedance is required, then the value of the inductance that needs to be introduced in…2022 · 28 Jun · Shift 1 · Q69 · Numerical
In the given circuit, the magnitude of VL and VC are twice that of VR. Given that f = 50 Hz, the inductance of the coil is $\frac{1}{K π}$ mH. The value of K is . Includes diagram2022 · 28 Jun · Shift 2 · Q71 · Numerical
An alternating emf $E = 440 sin 100 π t$ is applied to a circuit containing an inductance of $\frac{2}{π} H$ . If an a.c. ammeter is connected in the circuit, its reading will be :2022 · 29 Jul · Shift 1 · Q60 · MCQ
A coil of inductance 1 H and resistance $100 Ω$ is connected to a battery of 6 V. Determine approximately : (a) The time elapsed before the current acquires half of its steady - state value. (b) The energy stored in the magnetic…2022 · 29 Jul · Shift 1 · Q61 · MCQ
A circuit element $X$ when connected to an a.c. supply of peak voltage $100 V$ gives a peak current of $5 A$ which is in phase with the voltage. A second element $Y$ when connected to the same a.c.…2022 · 29 Jul · Shift 2 · Q51 · MCQ
A capacitor of capacitance 500 $μ$ F is charged completely using a dc supply of 100 V. It is now connected to an inductor of inductance 50 mH to form an LC circuit. The maximum current in LC circuit will be A.2022 · 29 Jul · Shift 2 · Q69 · Numerical
For a series LCR circuit, I vs $ω$ curve is shown : (a) To the left of $ω$ r, the circuit is mainly capacitive. (b) To the left of $ω$ r, the circuit is mainly inductive. (c) At $ω$ r, impedance of the circuit is equal… Includes diagram2022 · 29 Jun · Shift 1 · Q50 · MCQ
An inductor of 0.5 mH, a capacitor of 200 $μ$ F and a resistor of 2 $Ω$ are connected in series with a 220 V ac source. If the current is in phase with the emf, the frequency of ac source will be $\times$ …2022 · 29 Jun · Shift 2 · Q70 · Numerical
In series RLC resonator, if the self inductance and capacitance become double, the new resonant frequency (f2) and new quality factor (Q2) will be : (f1 = original resonant frequency, Q1 = original quality factor)2022 · 30 Jun · Shift 1 · Q56 · MCQ
A series LCR circuit with $R = \frac{250}{11} Ω$ and $X_{L} = \frac{70}{11} Ω$ is connected across a 220 V, 50 Hz supply. The value of capacitance needed to maximize the average power of the circuit will be …2022 · 30 Jun · Shift 1 · Q64 · Numerical
For the given circuit the current i through the battery when the key in closed and the steady state has been reached is . Includes diagram2021 · 1 Sep · Shift 2 · Q59 · MCQ
An RC circuit as shown in the figure is driven by a AC source generating a square wave. The output wave pattern monitored by CRO would look close to : Includes diagram2021 · 16 Mar · Shift 1 · Q58 · MCQ
A sinusoidal voltage of peak value 250 V is applied to a series LCR circuit, in which R = 8 $Ω$ , L = 24 mH and C = 60 $μ$ F. The value of power dissipated at resonant condition is 'x' kW. The value of x to the nearest integer is …2021 · 16 Mar · Shift 1 · Q67 · Numerical
For the given circuit, comment on the type of transformer used. Includes diagram2021 · 16 Mar · Shift 2 · Q61 · MCQ
An AC current is given by I = I1 sin $ω$ t + I2 cos $ω$ t. A hot wire ammeter will give a reading :2021 · 17 Mar · Shift 1 · Q55 · MCQ
Match List - I with List - II Choose the most appropriate answer from the options given below : Includes table2021 · 17 Mar · Shift 2 · Q45 · MCQ
What happens to the inductive reactance and the current in a purely inductive circuit if the frequency is halved?2021 · 17 Mar · Shift 2 · Q51 · MCQ
In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value :2021 · 18 Mar · Shift 1 · Q57 · MCQ
An AC source rated 220 V, 50 Hz is connected to a resistor. The time taken by the current to change from its maximum to the rms value is :2021 · 18 Mar · Shift 1 · Q58 · MCQ
In a series LCR circuit, the inductive reactance (XL) is 10 $Ω$ and the capacitive reactance (XC) is 4 $Ω$ . The resistance (R) in the circuit is 6 $Ω$ . The power factor of the circuit is :2021 · 18 Mar · Shift 2 · Q47 · MCQ
AC voltage V(t) = 20 sin $ω$ t of frequency 50 Hz is applied to a parallel plate capacitor. The separation between the plates is 2 mm and the area is 1 m2. The amplitude of the oscillating displacement current for the applied AC…2021 · 20 Jul · Shift 1 · Q60 · MCQ
In an LCR series circuit, an inductor 30 mH and a resistor 1 $Ω$ are connected to an AC source of angular frequency 300 rad/s. The value of capacitance for which, the current leads the voltage by 45 $^{\circ}$ is $\frac{1}{x} \times 1 0^{- 3}$ …2021 · 20 Jul · Shift 1 · Q69 · Numerical
For a series LCR circuit with R = 100 $Ω$ , L = 0.5 mH and C = 0.1 pF connected across 220V $-$ 50 Hz AC supply, the phase angle between current and supplied voltage and the nature of the circuit is :2021 · 20 Jul · Shift 2 · Q52 · MCQ
A series LCR circuit of R = 5 $Ω$ , L = 20 mH and C = 0.5 $μ$ F is connected across an AC supply of 250 V, having variable frequency. The power dissipated at resonance condition is $\times$ 102 W.2021 · 20 Jul · Shift 2 · Q69 · Numerical
In a circuit consisting of a capacitance and a generator with alternating emf Eg = Eg0 sin $ω$ t, VC and IC are the voltage and current. Correct phasor diagram for such circuit is Includes diagram2021 · 22 Jul · Shift 2 · Q49 · MCQ
Match List - I with List - II Choose the correct answer from the options given below Includes table2021 · 22 Jul · Shift 2 · Q58 · MCQ
A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns…2021 · 24 Feb · Shift 1 · Q68 · Numerical
A series L-C-R circuit is designed to resonate at an angular frequency $ω$ 0 = 105 rad/s. The circuit draws 16W power from 120V source at resonance. The value of resistance 'R' in the circuit is $Ω$ .2021 · 24 Feb · Shift 2 · Q66 · Numerical
The angular frequency of alternating current in a L-C-R circuit is 100 rad/s. The components connected are shown in the figure. Find the value of inductance of the coil and capacity of condenser. Includes diagram2021 · 25 Feb · Shift 1 · Q49 · MCQ
The current (i) at time t = 0 and t = $\infty$ respectively for the given circuit is : Includes diagram2021 · 25 Feb · Shift 1 · Q62 · MCQ
A transmitting station releases waves of wavelength 960 m. A capacitor of 2.56 $μ$ F is used in the resonant circuit. The self inductance of coil necessary for resonance is $\times$ 10 $-$ 8 H.2021 · 25 Feb · Shift 1 · Q72 · Numerical
An LCR circuit contains resistance of 110 $Ω$ and a supply of 220 V at 300 rad/s angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45 $^{\circ}$ . If on the other hand, only inductor…2021 · 25 Feb · Shift 2 · Q49 · MCQ
Match List I with List II. Choose the correct answer from the options given below : Includes table2021 · 25 Feb · Shift 2 · Q56 · MCQ
An inductor of 10 mH is connected to a 20V battery through a resistor of 10 k $Ω$ and a switch. After a long time, when maximum current is set up in the circuit, the current is switched off. The current in the circuit after 1 $μ$ s…2021 · 25 Jul · Shift 1 · Q64 · Numerical
A 10 $Ω$ resistance is connected across 220V $-$ 50 Hz AC supply. The time taken by the current to change from its maximum value to the rms value is :2021 · 25 Jul · Shift 2 · Q52 · MCQ
Two circuits are shown in the figure (a) & (b). At a frequency of rad/s the average power dissipated in one cycle will be same in both the circuits. Includes diagram2021 · 25 Jul · Shift 2 · Q67 · Numerical
A series LCR circuit driven by 300 V at a frequency of 50 Hz contains a resistance R = 3 k $Ω$ , an inductor of inductive reactance XL = 250 $π Ω$ and an unknown capacitor. The value of capacitance to maximize the average power…2021 · 26 Aug · Shift 1 · Q50 · MCQ
In the given circuit the AC source has $ω$ = 100 rad s-1. Considering the inductor and capacitor to be ideal, what will be the current I flowing through the circuit? Includes diagram2021 · 26 Aug · Shift 2 · Q60 · MCQ
An alternating current is given by the equation i = i1 sin $ω$ t + i2 cos $ω$ t. The rms current will be :2021 · 26 Feb · Shift 1 · Q45 · MCQ
In a series LCR resonant circuit, the quality factor is measured as 100. If the inductance is increased by two fold and resistance is decreased by two fold, then the quality factor after this change will be .2021 · 26 Feb · Shift 1 · Q66 · Numerical
Find the peak current and resonant frequency of the following circuit (as shown in figure). Includes diagram2021 · 26 Feb · Shift 2 · Q50 · MCQ
The alternating current is given by $i = {42 sin (\frac{2 π}{T} t) + 10} A$ The r.m.s. value of of this current is ................. A.2021 · 27 Aug · Shift 1 · Q60 · Numerical
An ac circuit has an inductor and a resistor resistance R in series, such that XL = 3R. Now, a capacitor is added in series such that XC = 2R. The ratio of new power factor with the old power factor of the circuit is $5 : x$ . The…2021 · 27 Aug · Shift 2 · Q64 · Numerical
A 0.07 H inductor and a 12 $Ω$ resistor are connected in series to a 220V, 50 Hz ac source. The approximate current in the circuit and the phase angle between current and source voltage are respectively. [Take $π$ as ${{22} \over…2021 · 27 Jul · Shift 1 · Q63 · MCQ
Consider an electrical circuit containing a two way switch 'S'. Initially S is open and then T1 is connected to T2. As the current in R = 6 $Ω$ attains a maximum value of steady state level, T1 is disconnected from T2 and immediately… Includes diagram2021 · 27 Jul · Shift 1 · Q66 · Numerical
A 100 $Ω$ resistance, a 0.1 $μ$ F capacitor and an inductor are connected in series across a 250 V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant…2021 · 27 Jul · Shift 2 · Q52 · MCQ
In an ac circuit, an inductor, a capacitor and a resistor are connected in series with XL = R = XC. Impedance of this circuit is :2021 · 31 Aug · Shift 1 · Q61 · MCQ
At very high frequencies, the effective impendence of the given circuit will be $Ω$ . Includes diagram2021 · 31 Aug · Shift 2 · Q69 · Numerical
An inductance coil has a reactance of 100 $Ω$ . When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45o. The self-inductance of the coil is2020 · 2 Sep · Shift 2 · Q43 · MCQ
A 750 Hz, 20 V (rms) source is connected to a resistance of 100 $Ω$ , an inductance of 0.1803 H and a capacitance of 10 $μ$ F all in series. The time in which the resistance (heat capacity 2 J/oC) will get heated by 10oC. (assume no…2020 · 3 Sep · Shift 1 · Q60 · MCQ
A series L-R circuit is connected to a battery of emf V. If the circuit is switched on at t = 0, then the time at which the energy stored in the inductor reaches $(\frac{1}{n})$ times of its maximum value, is :2020 · 4 Sep · Shift 2 · Q56 · MCQ
In a series LR circuit, power of 400W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0.8. In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the…2020 · 6 Sep · Shift 2 · Q49 · Numerical
A LCR circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant 'b', the correct equivalence would be:2020 · 7 Jan · Shift 1 · Q53 · MCQ
An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 $Ω$ resistor. The ratio of the currents at time t = $\infty$ and at t = 40 s is close to : (Take e2 = 7.389)2020 · 7 Jan · Shift 2 · Q55 · MCQ
In LC circuit the inductance L = 40 mH and capacitance C = 100 $μ$ F. If a voltage V(t) = 10sin(314t) is applied to the circuit, the current in the circuit is given as :2020 · 9 Jan · Shift 2 · Q58 · MCQ
An alternating voltage v(t) = 220 sin 100 $π$ t volt is applied to a purely resistance load of 50 $Ω$ . The time taken for the current to rise from half of the peak value to the peak value is :2019 · 8 Apr · Shift 1 · Q46 · MCQ
A circuit connected to an ac source of emf e = e0sin(100t) with t in seconds, gives a phase difference of $π$ /4 between the emf e and current i. Which of the following circuits will exhibit this ?2019 · 8 Apr · Shift 2 · Q50 · MCQ
A series AC circuit containing an inductor (20 mH), a capacitor (120 $μ$ F) and a resistor (60 $Ω$ ) is driven by an AC source of 24V/50 Hz. The energy dissipated in the circuit in 60 s is :2019 · 9 Jan · Shift 2 · Q52 · MCQ
A power transmission line feeds input power at 2300 V to a srep down transformer with its primary windings having 4000 turns. The output power is delivered at 230 V by the transformer. If the current in the primary of the transformer is 5A…2019 · 9 Jan · Shift 2 · Q71 · MCQ
A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10A, then the input voltage and current in the primary coil are :2019 · 10 Apr · Shift 1 · Q48 · MCQ
A coil of self inductance 10 mH and resistance 0.1 $Ω$ is connected through a switch to a battery of internal resistance 0.9 $Ω$ . After the switch is closed, the time taken for the current to attain 80% of the saturation value…2019 · 10 Apr · Shift 2 · Q62 · MCQ
In the circuit shown, the switch S1 is closed at time t = 0 and the switch S2 is kept open. At some later time(t0), the switch S1 is opened and S2 is closed. The behavior of the current I as a function of time 't' is given by : Includes diagram2019 · 11 Jan · Shift 1 · Q51 · MCQ
Consider the LR circuit shown in the figure. If the switch S is closed at t = 0 then the amount of charge that passes through the battery between t = 0 and t = $\frac{L}{R}$ is : Includes diagram2019 · 12 Apr · Shift 2 · Q56 · MCQ
In the figure shown, a circuit contains two identical resistors with resistance R = 5 $Ω$ and an inductance with L = 2mH. An ideal battery of 15 V is connected in the circuit. What will be the current through the battery long after… Includes diagram2019 · 12 Jan · Shift 1 · Q53 · MCQ
In the above circuit, C = $\frac{3}{2} μ$ F, R2 = 20 $Ω$ , L = $\frac{3}{10}$ H and R1 = 10 $Ω$ . Current in L-R1 path is I1 and in C-R2 path it is I2 . The voltage of A.C. source is given by, V = 200 $2$ … Includes diagram2019 · 12 Jan · Shift 2 · Q70 · MCQ
An ideal capacitor of capacitance $0.2 μ F$ is charged to a potential difference of $10 V .$ The charging battery is then disconnected. The capacitor is then connected to an ideal inductor of self inductance $0.5 m H .$ The current at a time…2018 · 15 Apr · Shift 1 · Q71 · MCQ
A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns, giving the output power at 230 V. If the current in the primary of the transformer is 5 A, and its efficiency is…2018 · 16 Apr · Shift 1 · Q56 · MCQ
In an a.c. circuit, the instantaneous e.m.f. and current are given by e = 100 sin 30 t i = 20 sin $(30 t - \frac{π}{4})$ In one cycle of a.c., the average power consumed by the circuit and the wattless current are,…2018 · Shift 0 · Q48 · MCQ
A sinusoidal voltage of peak value 283 V and angular frequency 320/s is applied to a series LCR circuit. Given that R=5 $Ω$ , L=25 mH and C=1000 $μ$ F. The total impedance, and phase difference between the voltage across the source…2017 · 9 Apr · Shift 1 · Q58 · MCQ
A series LR circuit is connected to a voltage source with V(t) = V0 sin $Ω$ t. After very large time, current I(t) behaves as (t0 >> $\frac{L}{R}$ ) :2016 · 9 Apr · Shift 1 · Q69 · MCQ
An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to :2016 · Shift 0 · Q43 · MCQ
An inductor $(L = 0.03 H)$ and a resistor $(R = 0.15 k Ω)$ are connected in series to a battery of $15 V E M F$ in a circuit shown below. The key $K_{1}$ has been kept closed for a long time. Then at $t = 0$ , $K_{1}$ is… Includes diagram2015 · Shift 0 · Q46 · MCQ
An $L C R$ circuit is equivalent to a damped pendulum. In an $L C R$ circuit the capacitor is charged to $Q_{0}$ and then connected to the $L$ and $R$ as shown below : If a student plots graphs of the square of maximum charge $(Q_{M a x}^{2})$ … Includes diagram2015 · Shift 0 · Q47 · MCQ
In the circuit shown here, the point $^{'} C^{'}$ is kept connected to point $^{'} A^{'}$ till the current flowing through the circuit becomes constant. Afterward, suddenly, point $^{'} C^{'}$ is disconnected from point $^{'} A^{'}$ and connected to point $^{'} B^{'}$ at… Includes diagram2014 · Shift 0 · Q51 · MCQ
In an $L C R$ circuit as shown below both switches are open initially. Now switch $S_{1}$ is closed, $S_{2}$ kept open. ( $q$ is charge on the capacitor and $τ = R C$ is Capacitance time constant). Which of the following statement is correct… Includes diagram2013 · Shift 0 · Q56 · MCQ
A resistor $^{'} R^{'}$ and $2 μ F$ capacitor in series is connected through a switch to $200 V$ direct supply. Across the capacitor is a neon bulb that lights up at $120 V .$ Calculate the value of $R$ to make the bulb light up $5 s$ after the…2011 · Shift 0 · Q58 · MCQ
A fully charged capacitor $C$ with initial charge $q_{0}$ is connected to a coil of self inductance $L$ at $t = 0.$ The time at which the energy is stored equally between the electric and the magnetic fields is :2011 · Shift 0 · Q60 · MCQ
In the circuit shown below, the key $K$ is closed at $t = 0.$ The current through the battery is Includes diagram2010 · Shift 0 · Q56 · MCQ
In a series $L C R$ circuit $R = 200Ω$ and the voltage and the frequency of the main supply is $220 V$ and $50 H z$ respectively. On taking out the capacitance from the circuit the current lags behind the voltage by $3 0^{\circ} .$ On…2010 · Shift 0 · Q65 · MCQ
An inductor of inductance $L = 400 m H$ and resistors of resistance $R_{1} = 2Ω$ and $R_{2} = 2Ω$ are connected to a battery of $e m f 12 V$ as shown in the figure. The internal resistance of the battery is negligible. The switch $S$ is… Includes diagram2009 · Shift 0 · Q54 · MCQ
In an $a . c .$ circuit the voltage applied is $E = E_{0} sin ω t .$ The resulting current in the circuit is $I = I_{0} sin (ω t - \frac{π}{2}) .$ The power consumption in the circuit is given by2007 · Shift 0 · Q71 · MCQ
In an $A C$ generator, a coil with $N$ turns, all of the same area $A$ and total resistance $R,$ rotates with frequency $ω$ in a magnetic field $B .$ The maximum value of $e m f$ generated in the coil is2006 · Shift 0 · Q93 · MCQ
In a series resonant $L C R$ circuit, the voltage across $R$ is $100$ volts and $R = 1 k Ω$ with $C = 2 μ F .$ The resonant frequency $ω$ is $200 r a d / s$ . At resonance the voltage across $L$ is2006 · Shift 0 · Q94 · MCQ
The self inductance of the motor of an electric fan is $10 H$ . In order to impart maximum power at $50 H z$ , it should be connected to a capacitance of2005 · Shift 0 · Q129 · MCQ
A circuit has a resistance of $12 o hm$ and an impedance of $15 o hm$ . The power factor of the circuit will be2005 · Shift 0 · Q131 · MCQ
The phase difference between the alternating current and $e m f$ is $\frac{π}{2} .$ Which of the following cannot be the constituent of the circuit?2005 · Shift 0 · Q132 · MCQ
Alternating current can not be measured by $D . C .$ ammeter because2004 · Shift 0 · Q147 · MCQ
In an $L C R$ series $a . c .$ circuit, the voltage across each of the components, $L, C$ and $R$ is $50 V$ . The voltage across the $L . C$ combination will be :2004 · Shift 0 · Q148 · MCQ
In a $L C R$ circuit capacitance is changed from $C$ to $2 C$ . For the resonant frequency to remain unchaged, the inductance should be changed from $L$ to2004 · Shift 0 · Q152 · MCQ
In an oscillating $L C$ circuit the maximum charge on the capacitor is $Q$ . The charge on the capacitor when the energy is stored equally between the electric and magnetic field is2003 · Shift 0 · Q137 · MCQ
The core of any transformer is laminated so as to2003 · Shift 0 · Q138 · MCQ
The power factor of $A C$ circuit having resistance $(R)$ and inductance $(L)$ connected in series and an angular velocity $ω$ is2002 · Shift 0 · Q127 · MCQ
In a transformer, number of turns in the primary coil are $140$ and that in the secondary coil are $280.$ If current in primary coil is $4 A,$ then that in the secondary coil is2002 · Shift 0 · Q128 · MCQ