In an ac circuit the potential difference V and current I are given respectively by V = 100 sin (100 t) volt and I = 100 sin 100 t + π 3 m A .The power dissipated in the circuit will be
In an ac circuit containing a resistor and an inductor connected in series, supply voltage (v) and resulting current are given by v = 100 sin 200t volt and i = 50 sin (200t – π /3) Amp. Then the resistance of the resistor is
If power factor is 1/2 of a series RL AC circuit, where R = 100 Ω and supply frequency is 50 Hz then L is
Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?
The variation of EMF with time for four types of generators are shown in the figures. Which amongst them can be called AC?
A transformer having efficiency of 90% is working on 200V and 3kW power supply. If the current in the secondary coil is 6A, the voltage across the secondary coil and the current in the primary coil respectively are :
The rms value of potential difference V shown in the fig. 10.56 is :
In the circuit shown, assuming all ammeters to be ideal, if readings of the hot wire ammeters A 1 and A 2 are i 1 and i 2 respectively then reading of the hot wire ammeter A 3 is :
An electrical device operates at 12 A current and 120 V dc. it is connected with 250 V and 30 Hz ac. The power consumption will :
A condenser of capacity 6μF is fully charged using a 6 volt battery. The battery is removed and a resistanceless 0.2 mH inductor is connected across the condenser. The current which is flowing through the inductor when one-third of the total energy is in the magnetic field of the inductor is :
If i = t 2 , and 0 < t < T , then r.m.s. value of current is
If an AC main supply is given to be 220 V, then what would be the average e.m.f. during a positive half cycle?
There is a 5 Ω resistance in an AC circuit. Inductance of 0.1 H is connected with it in series. If equation of AC e.m.f. is 5 sin (50t), then the phase difference between current and e.m.f. is
An e.m.f. E = 4 cos (1000t) volt is applied to an LR circuit of inductance 3 mH and resistance 4 ohms. The amplitude of current in the circuit is
The reactance of a coil when used in the domestic AC power supply (220 volt, 50 cycles) is 100 ohm. The self-inductance of the coil is nearly (Assume negligible resistance of coil)
In a circuit containing an inductance of zero resistance, the e.m.f. of the applied AC voltage leads the current by
A constant voltage at different frequencies is applied across a capacitance C as shown in the figure. Which of the following graphs correctly depicts the variation of current with frequency?
For high frequency, a capacitor offers
For a series RLC circuit, R = X L = 2 X C . The impedance of the circuit and phase difference between V and i will be
In the circuit shown in figure, the frequency of source voltage is ω = 2000 rad / s . The amplitude of the current will be nearest to
Two resistors are connected in series across 5 volt r.m.s. source of alternating potential as shown in figure. The potential difference across 6 Ω resistor is 3V. If R is replaced by pure inductor L of such magnitude that current remains same, potential difference across L is
A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 Ω . When an AC e.m.f. of 220 V 50 Hz is applied to it, find the wattless component of current in the circuit is
A telephone wire of length 200 km has a capacitance of 0 .014 μF per km. If it carries an AC of frequency 5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum?
In the circuit shown in the figure, the AC source gives a voltage V = 20 cos ( 2000 t ) . Neglecting source resistance, the voltmeter and ammeter reading will be
In the adjoining figure, the impedance of the circuit will be
Power factor is maximum in an LCR circuit when
In a circuit, the current lags behind the voltage by a phase difference of π / 2 . The circuit will contain which of the following?
Statement 1: In a series LCR circuit at resonance condition, power consumed by the circuit is maximum. Statement 2: At resonance condition, effective resistance of circuit is maximum.
The ratio of turns in primary to that in secondary for a transformer is 5 : 1 and power delivered by it is 500 W. What is the current in primary coil if a current of 12.5 A is flowing in the secondary coil?
An inductive coil and resistance of 100 Ω . When an ac signal of frequency 1000 Hz is fed to the coil, the applied voltage leads the current by 45 o . What is the inductance of the coil?
A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are
A small signal voltage V ( t ) = V 0 sin ωt is applied across an ideal capacitor C
The power factor of a series RL circuit is 1 2 . If the frequency of the applied ac is doubled, the power factor become.
A series R-C circuit is connected to an alternating voltage source. Consider two situations: (a) When capacitor is air filled. (b) When capacitor is mica filled. Current through resistor is i and voltage across capacitor is V then
The potential differences across the resistance, capacitance and inductance are 80 V , 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is
Power factor of the A.C. circuit as shown in the figure is
The secondary coil of an ideal step down transformer is delivering 500 watt power at 12.5 A current. If the ratio of turns in the primary to the secondary is 5: 1, then the current flowing in the primary coil will be :
A bulb is rated at 100V, 100W, it can be treated as a resistor. Find out the inductance of an inductor (called choke coil) that should be connected in series with the bulb to operate the bulb at its rated power with the help of an ac source of 200V and 50 Hz.
A circuit when connected to an AC source of 12 V gives a current of 0.2 A. The same circuit when connected to a DC source of 12 V, gives a current of 0.4 A. The circuit is
Current and voltage in AC are i = i 0 sin ωt − π 4 and V = V 0 sin ωt + π 4 Then
The power factor of an LR ac circuit is 1 2 and resistance of the circuit is R. The reactance of a capacitor should be connected in series in this circuit so that the power factor of the circuit will become one..
An AC source has an internal resistance of 10 4 Ω . The turn ratio of a transformer so as to match the source to a load of resistance 10 Ω is
An inductive coil has resistance of 100 Ω . When an ac signal of frequency 1000 Hz is fed to the coil, the applied voltage leads the current by 45°. What is the inductance of the coil?
A resistor and an inductor are connected to an ac supply of 120 V and 50 Hz. The current in the circuit is 3 (A) If the power consumed in the circuit is 108 W, then the resistance in the circuit is
In a series L – C – R circuit frequency of the source is constant and power dissipated in the circuit is maximum when L = 80 mH and C = 100 μ F . If inductance of the inductor is changed to 100 mH, what will be the capacitance of the capacitor for which the power dissipated in the circuit will be again maximum ?
In the net work shown if X C = R 2 a n d X L = R , ratio of power consumed in the upper branch to that in the lower branch is
An inductive coil has a resistance of 100 ohms. When an ac signal of frequency 1000 Hz is fed to the coil, the applied voltage leads the current by 45 0 . What is the inductance of the coil?
A 200 watt bulb is connected in secondary coil. Its primary is connected at 400 volt. If efficiency of transformer is 80% and the bulb is running with its peak power then, the current in primary coil is
A 200 watt bulb is connected in secondary coil. Its primary is connected at 400 volt. If efficiency of transformer is 80% and the bulb is running with its peak power then, the current in A in primary coil is
A given LCR series circuit satisfies the condition for resonance with a given AC source. If the angular frequency of the AC source is increased by 100% then in order to establish resonance, without changing the value of inductance, the capacitance must be
The graph of alternating emf versus time is shown in the figure. The average of this alternating emf in the first one-half cycle will be
In the circuit shown in the figure, the ac source gives a voltage Neglecting source resistance, the voltmeter and ammeter reading will be
A bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased, while keeping the voltage of the source constant, then
A telephone wire of length 200 km has a capacitance of 0.014 µF per km. If it carries an ac of frequency 5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum
In the circuit shown in figure neglecting source resistance the voltmeter and ammeter reading will respectively, be
An ac source of angular frequency ω is fed across a resistor r and a capacitor C in series. The current registered is I. If now the frequency of source is changed to ω/3 (but maintaining the same voltage), the current in then circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency ω.
In the series LCR circuit, the voltmeter and ammeter readings are respectively:
In the adjoining ac circuit the voltmeter whose reading will be zero at resonance is
An alternating emf is applied across a parallel combination of a resistance R, capacitance C and an inductance L. If I R , I L , I C are the currents through R, L and C respectively, then the diagram which correctly represents, the phase relationship among I R , I L , I C and source emf E, is given by
If then r.m.s. value of current is
An ac source of variable frequency f is connected to an LCR series circuit. Which one of the graphs in figure represents the variation of current I in the circuit with frequency f
Which one of the following curves represents the variation of impedance (Z) with frequency f in series LCR circuit
The r.m.s. voltage of the wave form shown is
A 150 π m H inductor is connected to a 200 V, 50 Hz alternating supply. Then the rms value of current in the circuit is
When an inductor and resistor (R) are connected in series, and the combination is connected to a 200 volt, 50 Hz A.C. supply, the phase difference between the current and voltage is found to be 60 o . If the resistance of the resistor is 50 Ω , the rms value of current in the circuit is
An alternating source of emf v = 10 cos 100 π t volt is connected across a R – L series circuit. If the phase difference between the resulting current and supply voltage is 60 o and R = 1 Ω , the rms value of current in the circuit is
In a circuit L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45°. The value of C is :
A series LCR circuit is connected to ac source of variable frequency ‘f ‘. The graphical representation of variation of impedance ‘z’ of the circuit with frequency f will be :
The mean and rms value of an alternating voltage for half cycle as shown in figure are respectively :
In the given figure if i 1 = 3sin ω t and i 2 = 4cos ω t, then i 3 is :
A generator produces a voltage that is given by V = 240 sin 120t, where t is in seconds. The frequency and r.m.s. voltage are
The output current versus time curve of a rectifier is shown in the figure. The average value of output current in this case is
A resistance of 20 ohms is connected to a source of an alternating potential V = 220 sin ( 100 πt ) The time taken by the current to change from its peak value to r.m.s. value is
The reactance of a 25 μF capacitor at an AC frequency of 4000 Hz is
A capacitor is a perfect insulator for
In a series circuit, R = 300 Ω , L = 0 .9 H , C = 2 .0 μF and ω = 1000 rad / sec . The impedance of the circuit is
An inductive circuit contains resistance of 10 Ω and an inductance of 20 H. If an AC voltage of 120 V and frequency 60 Hz is applied to this circuit, the current would be nearly
An inductor of inductance of 1 mH, a capacitor of capacitance of 10 μF and a resistor resistance of 50 Ω are connected in series. The reactances of inductor and capacitor are same. The reactance of either of them will be
A circuit has a resistance of 11 Ω , an inductive reactance of 25 Ω and a capacitive resistance of 18 Ω . It is connected to an AC source of 260 V and 50 Hz. The current through the circuit (in amperes) is
In an AC circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current is 45 0 , the value of inductive reactance will be
An AC circuit consists of an inductor of inductance 0.5 H and a capacitor of capacitance 8 μF in series. The current in the circuit is maximum when the angular frequency of AC source is
A 20 volts AC is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V, the voltage across the coil is
An alternating voltage is connected in series with a resistance R and an inductance L. If the potential drop across the resistance is 200 V and across the inductance is 150 V, then the applied voltage is
The phase difference between the current and voltage of LCR circuit in series combination at resonance is
In an LCR circuit, the potential difference between the terminals of the inductance is 60 V between the terminals of the capacitor is 30V and that between the terminals of resistance is 40V. The supply voltage will be equal to
The current in series LCR circuit will be maximum when ω is
When an AC source of e.m. f. e = E 0 sin ( 100 t ) is connected across a circuit, the phase difference between the e.m.f. e and the current i in the circuit is observed to be π / 4 , as shown in the diagram. If the circuit consists possibly only of RC or RL in series, find the relationship between the two elements.
The inductance of a choke coil is 0.1 H and resistance is 12 Ω . If it is connected to an alternating current source of frequency 60 Hz, then power factor will be
A sinusoidal current flows through a resistor of resistance R. If the peak current is I p , then the power dissipated is
In an AC circuit, V and I are given by V = 100 sin ( 100 t ) volts, I = 100 sin 100 t + π 3 mA . The power dissipated in the circuit is
What is the r.m.s. value of an alternating current which when passed through a resistor produces heat which is thrice of that produced by a direct current of 2 amperes in the same resistor?
2 .5 π μF capacitor and 3000 ohm resistor are joined in series to an AC source of 200 volt and 50 sec − 1 frequency. The power factor of the circuit and the power dissipated in it will respectively be
An r.m.s. volt age of 110 V is applied across a series circuit having a resistance 11 Ω and impedance 22 Ω . The power consumed is
In the circuit given below, what will be the reading of the voltmeter?
In a circuit, L, C and R are connected in series with an alternating voltage source of frequency f. The current lags the voltage by 45 0 . The value of C is
A coil of inductive reactance 31 Ω has a resistance of 8 Ω . It is placed in series with a condenser of capacitive reactance 25 Ω . The combination is connected to an AC source of 110 V. The power factor of the circuit is
A lamp consumes only 50% of peak power in an a.c. circuit. What is the phase difference between the applied voltage and the circuit current?
A capacitor of capacitance 2 μF is connected in the tank circuit of an oscillator oscillating with a frequency of 1 kHz. If the current flowing in the circuit is 2 mA, the voltage across the capacitor will be
For the circuit shown in the figure, the current through the inductor is 0.9 A while the current through the condenser is 0.4 A. Hence the current drawn from the generator is
An ideal choke takes a current of 10 A when connected to an AC supply of 125 volt and 50 Hz. A pure resistor under the same conditions takes a current of 12.5 A. If the two are connected to an AC supply of 100 volt and 40 Hz, then the current in series combination of above resistor and inductor is
An alternating current source of frequency 100 Hz is joined to a combination of a resistance, a capacitance and a coil in series. The potential difference across the coil, the resistance and the capacitor is 46V 8V and 40 V respectively. The electromotive force of alternating current source in volt is
The maximum value of AC voltage in u circuit is 707V. Its r.m.s. value is
Statement 1: Average value of AC over a complete cycle is always zero. Statement 2: Average value of AC is always defined over half cycle.
Statement 1: In a series LCR circuit at resonance condition, power consumed by the circuit is maximum. Statement 2: At resonance condition, effective resistance of circuit is maximum.
The power factor of LCR circuit at resonance is
A bulb and a capacitor are in series with an AC source. On increasing frequency, how will glow of the bulb change?
The average power dissipation in a pure capacitor in AC circuit is
fig shows a series L-C-R circuit connected to a variable frequency and 200 V source. What is the source frequency which drives the circuit at resonance ?
In the circuit the current flowing through resistance R at resonance is
A step-up transformer operates on a 200 V line and supplies to a load of 2 A. The ratio of primary to secondary windings is 1 : 25. The primary current is
One 10 V , 60 W bulb is to be connected to 100 V line. The required induction coil has self inductance of value
What is the resistance to be connected in series with a condenser of a capacity 5 μF so that the phase difference between the current and the applied voltage is 45 0 when the angular frequency of the applied voltage is 400 rads – 1
An inductor 20 m H , a capacitor 50 μ F and a resistor 40 Ω are connected in series across a source of emf V = 10 sin 340 t . The power loss in A.C. circuit is
An alternating voltage v = 300 2 sin ( 60 t ) (in volts) is connected across a 4 μ F capacitor through an a.c. ammeter. The reading of ammeter will be
An inductor 20 mH, a capacitor 100 μ F and a resistor 50 Ω are connected in series across a source of emf, V=10 sin 314 t . The power loss in the circuit is
A pure resistive circuit element X when connected to an AC supply of peak voltage 200V gives a peak current of 5A which is in phase with the voltage. A second circuit element Y, when connected to the same AC supply also gives the same value of peak current but the current lags behind by 900. If the series combination of X and Y is connected to the same supply, the rms value of current is
In the figure, which of the phasor diagram represents RLC circuit driven at resonance?
A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when
In an LCR-circuit the A.C voltage across resistor, inductor and capacitor are respectively 30V, 50V, and 90V. The P.D across the combination is
A resistance ‘R’ draws power ‘P’ when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes ‘Z’, the power drawn will be
The primary of a transformer when connected to a dc battery of 10 Volt draws a current of 1 mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The voltage in the secondary and the current drawn by the cricuit in the secondary are respectively
In a certain circuit current changes with time according to i = 2 t . r.m.s. value of current between t=1 to t=4s will be
In a series circuit C = 4 μ F , L = 2 m H and R = 20 Ω , when the current in the circuit is maximum, at that time the ratio of the energies stored in the capacitor and the inductor will be
A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is π 3 . If instead C is removed from the circuit, the phase difference is again π 3 between current and voltage. The power factor of the circuit is :
A 40 μF capacitor is connected to a 200 V , 50 Hz ac supply. The rms value of the current in the circuit is , nearly :
A light bulb and an inductor coil are connected to an ac source through a key as shown in the figure below. The key is closed and after sometime an iron rod is inserted into the interior of the inductor. The glow of the light bulb
In an LCR ac circuit, the resistance and reactances R , X C a n d X L are in the ratio 1 : 3 : 4 .The frequency of ac is f 0 . The resonant frequency of the circuit will be
An alternating emf of frequency 50Hz is applied to a series LCR circuit of resistance 20 Ω , an inductance of 100mH and a capacitor of 30mF. The correct statement of the following is
Which one of the following curves represents the variation of impedance (Z) with frequency f in series LCR circuit
A bulb connected in series with an air-cored solenoid is lit by an a.c. source. If a soft iron core is introduced in the solenoid, then
We have three devices, a capacitor of C = 1 μF , an inductor of L = 10mH and a resistor of ‘R’ Ω when C and R are used in series combination and an alternating source of emf is connected across it, current leads the supply voltage by 45 0 when L and R are used in series combination and the same supply voltage is applied across the combination, current lags the supply voltage by 45 0 . Then R is
The rms value of current given by i = 3 sin 100 πt + 4 sin 200 πt Amp . is
A resistance of 20 W is connected to a source of an alternating potential V = 220 sin (100 π t). The time taken by the current to change from the peak value to rms value, is
The value of current in two series LCR circuits at resonance is same. Then
When 100 volt DC is applied across a solenoid, a current of 1.0 amp flows in it. When 100 volt AC is applied across the same coil, the current drops to 0.5 amp. If the frequency of the AC source is 50 Hz then power factor of the circuit is
In the circuit shown below, what will be the reading of the voltmeter V 3 and ammeter A?
An inductance of 200 π m H a capacitance of 1 π m F and a resistance of 10 ohm are connected in series with an ac source of 220 V, 50 Hz. The phase angle of the circuit is
The peak voltage in the output of a half wave diode rectifier fed with a sinusoidal signal without filter is 10 volt. The d.c. component of output voltage is
Power factor of a L − R series circuit is 0.8. When a capacitor is connected in series with R and L, the power factor increases to unity. Then reactance of the capacitor is
When an ideal battery of emf of 10 volt is connected across an inductor, rate of energy dissipated in it is 10 Watt. When a 10 volt 50 Hz alternating source is connected across the same inductor, power consumed by the inductor is 2.5 Watt. Then reactance of the inductor is
A resistor R = 100 Ω is connected in series with a capacitor. A source of supply voltage e = 100 cos 100 πt volt is connected across the combination. If the current through the circuit is i = 4 2 cos 100 πt + π 4 A the value of capacitance is
An inductor is connected in series with a resistor. When a source of alternating voltage is connected across the combination, current is found to lag behind the voltage by an angle of 60 o . If R = 10 Ω and r.m.s. value of supply voltage is 100 volt, then the r.m.s. value of current in the circuit is
An R-C series circuit is connected to an alternating source of emf V = V 0 cos 100 πt , instantaneous current in the circuit is i = 5 cos 100 πt + π 4 A , the value of V 0 is [Resistance R used in the circuit is 10 Ω ]
A step down transformer reduces the voltage of a transmission line from 2200 V to 220 V. The power delivered by it is 880 W and its efficiency is 88%. The input current is
Current flowing through a 10 Ω resistor is given by i = ( 3 + 4 cos 100 π t ) A . Then average power consumed by the resistor is
Current through a circuit containing R and L or R and C or C and L is cos 100 π t − 3 . sin 100 π t A m p . Voltage applied across the combination is 100 cos 100 π t v o l t . Then power consumed by the circuit is
When LCR series circuit is in state of resonance, its resistance is doubled, then
Figure shows a series LCR circuit connected to a variable frequency 200V source. L = 5H, C = 80 µF and R = 40 Ω. What is the source frequency which drives the circuit at resonance?
In the LCR circuit, the voltmeter and ammeter readings are
In figure below if Z L = Z C and reading of ammeter is 1 A. Find value of source voltage V.
One 10 V , 60 W bulb is to be connected to 100 V line. The required induction coil has self inductance of value ( f = 50Hz )
In an LR-circuit, the inductive reactance is equal to the resistance R of the circuit. An e.m.f. E = Eo Cos(ωt) applied to the circuit. The power consumed in the circuit is
In the circuit shown below, what will be the readings of the voltmeter and ammeter
The voltage of an ac supply varies with time ( t ) as The maximum voltage and frequency respectively are
The voltage of an ac source varies with time according to the equation where t is in seconds and V is in volts. Then
The diagram shows a capacitor C and a resistor R connected in series to an ac source. V 1 and V 2 are voltmeters and A is an ammeter Consider now the following statements I. Readings in A and V 2 are always in phase II. Reading in V 1 is ahead in phase with reading in V 2 III. Readings in A and V 1 are always in phase which of these statements are/is correct
An alternating e.m.f. of angular frequency is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
In a certain circuit current changes with time according to r.m.s. value of current between t = 2 to t = 4s will be
In the circuit given below, what will be the reading of the voltmeter
The reading of ammeter in the circuit shown will be
Match the following Currents r.m.s. values (1) X o sin ωt (i) X o (2) X o sin ω t cos ω t (ii) (3) (iii)
An LCR series circuit with a resistance of 100 ohm is connected to an ac source of 200 V (r.m.s.) and angular frequency 300 rad/s. When only the capacitor is removed, the current lags behind the voltage by 60 o . When only the inductor is removed the current leads the voltage by 60 o . The average power dissipated is
For a series RLC circuit R = X L = 2X C . The impedance of the circuit and phase difference (between) V and i will be
A virtual current of 4A and 50 Hz flows in an ac circuit containing a coil. The power consumed in the coil is 240 W. If the virtual voltage across the coil is 100 V its inductance will be
In a series circuit and when the current in the circuit is maximum, at that time the ratio of the energies stored in the capacitor and the inductor will be
The figure shows variation of R, X L and X C with frequency f in a series L, C, R circuit. Then for what frequency point, the circuit is inductive
Two ends of a 10 Ω resistor is connected to an a.c. source whose voltage is given by V = 200 cos 100 π t V . Then power dissipated in the resistor is
In the circuit shown, inductance of the inductor L = 100 mH. Then average magnetic energy stored in the inductor is
A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 ampere, the efficiency of the transformer is approximately :
A transformer is used for a 100 watt, 20 volt electric bulb at a place where the A.C. mains potential is 200 volt and the current drawn is 0.6 A. The efficiency of the transformer is nearly :
A 220 volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volt. If the efficiency of the transformer is 80%, the current drawn by the primary winding of the transformer is :
An alternating voltage E (in volt) 200 2 sin ( 100t) is connected to a 1 μF capacitor through an ac ammeter. The reading of the ammeter shall be :
For a series LCR circuit, the power loss at resonance is :
Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt ac supply line. The power drawn by the combination in each case respectively will be :
In the given circuit the reading of voltmeter V 1 and V 2 are 300 volts each. The reading of the voltmeter V 3 and ammeter A are respectively : (supply voltage is 220 V )
An ac voltage is applied to a resistance R and inductor L in series. If Rand the inductive reactance are both equal to 3 Ω , the phase difference between the applied voltage and the current in the circuit is :
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 :
Consider following series RLC circuit. The maximum voltage drop across inductance is :
In the given circuit the potential difference across resistance is 54 V and power consumed by it is 16 W. If AC frequency is 60 Hz. Find the value of L :
An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf V = 10sin 340 t. The power loss in A.C. circuit is :
In series L-C-R circuit L = 10 mH, C = 10 μF, R = 20 Ω is connected to AC source of V = 200sin ω t. Find power at half power frequencies.
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is :
A coil has a resistance 10 Ω and an inductance of 0.4 Henry. It is connected to an AC source of 6.5 V, 30 π Hz. The average power consumed in the circuit, is :
In the shown AC circuit, the rms value of supply voltage is 130 volt. v 1 and v 2 are AC voltmeters. If reading of v 1 is 120 volt, reading of v 2 is
A transformer has an efficiency of 60% and works at 5kW. If the secondary voltage is 150 V, then what is the secondary current?
A 10 Ω resistor is carrying a current i = 3 + 4 2 sin 100 πt A then potential difference between the ends of the resistor measured by an a.c. ammeter is
The phasor diagram of the circuit containing an alternating source is as shown in the figure. Where Q represents rms value of current and P represents rms value of supply voltage. Then the circuit may contain
If the peak value of an alternating current is 6 A, then r.m.s. value of current will be
An AC is given by equation I = I 1 cosωt + I 2 sinωt The r.m.s. value of current is given by
The r.m.s. voltage of the waveform shown is
In a certain circuit, current changes with time according to i = 2 t . R.m.s. value of current between t = 2s to t = 4s will be
Match the following and choose the correct option from given codes. Currents R.m.s. values i. x 0 sinωt p. x 0 ii. x 0 sinωtcosωt q. x 0 2 iii. x 0 sinωt + x 0 cosωt r. x 0 2 2
A 40 Ω electric heater is connected to a 200 V 50 Hz mains supply. The peak value of electric current flowing in the circuit is approximately
The capacity of a pure capacitor is 1 farad. In DC circuits, its effective resistance will be
An alternating e.m.f. is applied to purely capacitive circuit. What is the phase relation between e.m.f. and current flowing in the circuit ?
A 120 volt AC source is connected across a pure inductor of inductance 0.70 henry. If the frequency of the source is 60 Hz, the current passing through the inductor is
The frequency for which a 5 μF capacitor has a reactance of 1 1000 ohm is
The value of the current through an inductance of 1 H and of negligible resistance, when connected through an AC source of 200 V and 50 Hz, is
The reactance of a coil when used in the domestic AC power supply (220 volts, 50 cycles per second) is 50 ohms. The inductance of the coil is nearly (Assume negligible resistance of coil)
The voltage across a pure inductor is represented by the following diagram. Which one of the following diagrams will represent the current?
The graphs given below depict the dependence of two reactive impedances X 1 and X 2 on the frequency of the alternating e.m.f. applied individually to them. We can then say that
Which of the following curves correctly represents the variation of capacitive reactance X C with frequency f ?
Reactance of an inductor, of 1 π henry at 50 Hz frequency is
Same current is flowing in two alternating circuits. The first circuit contains only inductor and the other contains only a capacitor. If the frequency of the e.m.f. of AC is increased, the effect on the value of the current will be
The figure shows variation of R, X L and X C with frequency f in a series L, C, R circuit. For what frequency point, the circuit is inductive?
In pure inductive circuit, the curves between frequency f and reciprocal of inductive reactance I/X L is
The instantaneous values of current and voltage in an AC circuit are i = 100 sin ( 314 t ) A and e = 200 sin ( 314 t + π / 3 ) V respectively. If the resistance is 1 Ω , then the reactance of the circuit will be
A resistance of 40 ohm and an inductance of 95.5 millihenry are connected in series in a 50 cycles/second AC circuit. The impedance of this combination is very nearly
The resistance of a coil for DC is R ohms. In AC, the resistance
An alternating current of frequency f is flowing in a circuit containing a resistance R and a choke Z in series. The impedance of this circuit is
If resistance of 100 Ω , inductance of 0.5 H and capacitance of 10 × 10 − 6 F are connected in series through 50 Hz AC supply, then impedance is
In a L-R circuit, the value of L is 0 .4 π henry and the value of R is 30 ohm. If in the circuit, an alternating e.m.f. of 200 volt at 50 cycles per sec is connected, the impedance of the circuit and current will respectively be
If an 8 Ω resistance and 6 Ω reactance are present in an AC series circuit, then the impedance of the circuit will be
A 220 V 50 Hz AC source is connected to an inductance of 0.2 H and a resistance of 20 ohm in series. What is the current in the circuit?
When 100 volt DC is applied across a coil, a current of 1 A flows through it. When 100 volt AC at 50 cycles/second is applied to the same coil, only 0.5 ampere current flows. The inductance of the coil is
In a series LCR circuit, resistance R = 10 Ω and the impedance Z = 20 Ω . The phase difference between the current and the voltage is
A bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased, while keeping the voltage of the source constant, then
In an AC circuit, the reactance of a coil is 3 times its resistance. The phase difference between the voltage across the coil to the current through the coil will be
Choke coil is used to control
A choke coil is preferred to a rheostat in AC circuit as
The vector diagram of current and voltage for a circuit is as shown. The components of the circuit will be
A resonant AC circuit contains a capacitor of capacitance 10 − 6 F and an inductor of 10 − 4 H . The frequency of electrical oscillations will be
A resistance of 300 Ω and an inductance of 1 π henry are connected in series to an AC voltage of 20 volts and 200 Hz frequency. The phase angle between the voltage and current is
An AC source of variable frequency f is connected to an LCR series circuit. which one of the graphs in figure represents the variation of current I in the circuit with frequency f ?
Which one of the following curves represents the variation of impedance (Z) with frequency f in series LCR circuit ?
L, C and R represent physical quantities inductance, capacitance and resistance, respectively. The combination representing dimension of frequency is
In a series resonant circuit, the AC voltage across resistance R, inductance L and capacitance C are 5 V 10 V and 10 V respectively. The AC voltage applied to the circuit is
An LCR circuit contains R = 50 Ω , L = 1 mH and C = 0 .1 μF . The impedance of the circuit will be minimum for a frequency of
The resonant frequency of a circuit is f. If the capacitance is made 4 times the initial values, then the resonant frequency will become
In an AC circuit, the potential difference across an inductance and resistance joined in series are respectively 16 V and 20 V respectively. The total potential difference across the circuit is
A series AC circuit consist of an inductor and a capacitor. The inductance and capacitance are respectively 1 henry and 25 μF . If the current is maximum in circuit, then angular frequency will be
A coil of 200 Ω resistance and 1.0 H inductance is connected to an AC source of frequency 200 / 2 π Hz . Phase angle between potential and current will be
A coil has L = 0.04 H and R = 12 Ω . When it is connected to 220V, 50Hz supply, the current flowing through the coil, in amperes, is
A coil of inductance L has an inductive reactance of X L in an AC circuit in which the effective current is I. The coil is made from a superconducting material and has no resistance. The rate at which power is dissipated in the coil is
The impedance of a circuit consists of 3 ohm resistance and 4 ohm reactance. The power factor of the circuit is
A virtual current of 4 A and 50 Hz flows in an AC circuit containing a coil. The power consumed in the coil is 240 W. If the virtual voltage across the coil is 100 V its inductance will be
One 10 V, 60 W bulb is to be connected to 100 V line. The required induction coil has self inductance of value (f = 50 Hz)
If a current I = I 0 sin ωt − π 2 flows in an AC circuit across which an AC potential of E = E 0 sin ωt has been applied, then the power consumption P in the circuit will be
In an AC circuit, the current is given by i = 5 sin 100 t − π 2 amperes and the AC potential is V = 200 sin ( 100 t ) volt. Then the power consumption is
In an AC circuit with voltage V and current I, the power dissipated is
In an AC circuit, the instantaneous values of e.m.f. and current are e = 200 sin (314t) volt and i = sin 314 t + π 3 amperes. The average power consumed in watt is
For an AC circuit, V = 15 sinωt and I = 20 cosωt . The average power consumed in this circuit is
An alternating e.m.f. of angular frequency ω is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
The power factor of a good choke coil is
What will be the phase difference between virtual voltage and virtual current, when the current in the circuit is wattless?
In an LR-circuit, the inductive reactance is equal to the resistance R of the circuit. An e.m.f. E = E 0 cos ( ωt ) applied to the circuit. The power consumed in the circuit is
An LCR series circuit with a resistance of 100 ohm is connected to an AC source of 200 V (r.m.s.) and angular frequency 300 rad/s. When only the capacitor is removed, the current lags behind the voltage by 60 0 . When only the inductor is removed the current leads the voltage by 60 0 . The average power dissipated is
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 watt. When it is connected with 10 volt AC source loss of power is 10 watt. The frequency of AC source will be
A resistor and an inductor are connected in series to a 220 volt AC supply. If the potential difference across resistor is 132 volt, then the potential difference across the terminals of the inductor is
In the given circuit , V C = 50 V and R = 50 Ω . The values of C and V R are
A220 V 50 Hz AC generator is connected to an inductor and a 50 Ω resistance in series. The current in the circuit is 1.0 A. What is the potential difference across inductor?
An 8 μF capacitor is connected across 220 V 50 Hz line. What is peak value of charge through capacitor?
A coil of inductance 0.1 H is connected to 50 V 100 Hz generator and current is found to be 0.5 A. The potential difference across resistance of coil is
In the figure shown, three AC voltmeters have been connected. At resonance, the reading of
If the instantaneous current in a circuit is given by i = 2 cos ( ωt − ϕ ) amperes, the r.m.s. value of the current is
A typical light dimmer, used to dim the stage lights in a theatre consists of a variable induction for L (where inductance is adjustable between zero and L max ), is connected in series with a light bulb B as shown. The mains electrical supply is 220 V at 50 Hz and the light bulb is rated at 220V, 1100 W. What L max is required if the rate of energy dissipation in the light bulb is to be varied by a factor of 5 from its upper limit of 1100 W?
The diagram shows a capacitor C and a resistor R connected in series to an AC source. V 1 and V 2 are voltmeters and A is an ammeter. Now, consider the following statements: I. Readings in A and V 2 are always in phase. II. Reading in V 1 is ahead in phase with reading in V 2 . lII. Readings in A and V 1 are always in phase. Which of these statements are/is correct?
In the circuit shown in figure, the voltmeter and ammeter reading will, respectively, be
The reading of voltmeter in the circuit shown will be
In the adjoining AC circuit, the voltmeter whose reading will be zero at resonance is
In a series circuit, C = 2 μF , L = 1 mH and R = 10 Ω . When the current in the circuit is maximum, at that time the ratio of the energies stored in the capacitor and the inductor will be
Power dissipated in an LCR series circuit connected to an AC source of emf ε is
In an ideal parallel LC circuit, the capacitor is charged by connecting it to a DC source which is then disconnected. The current in the circuit
An alternating emf is applied across a parallel combination of a resistance R, capacitance C and an inductance L. If I R , I L , I C the currents through R, L and C, respectively, then the diagram which correctly represents the phase relationship among I R , I L , I C and source emf E, is given by
An AC source of angular frequency ω is fed across a resistor R and a capacitor C in series. The current registered is I. If now the frequency of source is changed to ω /3 (but maintaining the same voltage), the current in the circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency.
Statement 1: In a purely resistive element of a series LCR AC circuit, the maximum value of r.m.s. current increases with increase in the angular frequency of the applied e.m.f. Statement 2: For an RLC circuit, I max = ε max Z , Z = R 2 + ωL − 1 ωC 2 , where I max is the peak current in a cycle.
Statement 1: When frequency is greater than resonant frequency in a series LCR circuit, it will be an inductive circuit. Statement 2: Resultant voltage leads the current in inductive circuits.
Statement 1: Capacitor serves as a block for DC and offers an easy path to AC. Statement 2: Capacitive reactance is inversely proportional to frequency.
Statement 1: If the frequency of alternating current in an AC circuit consisting of an inductance coil is increased, then current gets decreased. Statement 2: The current is inversely proportional to frequency of alternating current.
Statement 1: An inductor and a resistor are connected in series in an AC circuit. In this circuit, the current and the potential difference across the resistance lag behind potential difference across the inductance by an angle π / 2 . Statement 2: In an LR circuit, voltage leads the current by phase angle which depends on the value of inductance and resistance both.
Statement 1: An electric lamp connected in series with a variable capacitor and AC source, its brightness increases with increase in capacitance. Statement 2: Capacitive reactance decreases with increase in capacitance of capacitor.
In an AC circuit, peak value of voltage is 423 volts. Its effective voltage is
If instantaneous current is given by i = 4 cos ( ωt + ϕ ) amperes, then the r.m.s. value of current is
The power factor of an AC circuit having resistance R and inductance L connected in series and an angular velocity ω is
An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of emf V and frequency ω . Power dissipated in the circuit is
Alternating current can not be measured by DC ammeter because
In an LCR circuit, capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to
In an LCR series AC circuit, the voltage across each of the components L, C and R is 50V. The voltage across the LC combination will be
In a series LCR circuit, the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitance is short circuited, the voltage across the inductance will be
A direct current of 5 A is superimposed on an alternating current I = 10 sin ( ωt ) flowing through a wire. The effective value of the resulting current will be
A 10 Ω resistance, 5 mH coil and 10 μF capacitor are joined in series. When an alternating current source of suitable frequency is joined to this combination, the circuit resonates. If the resistance is halved, the resonance frequency
In an LCR circuit having L = 8 .0 H , C = 0 . 5 μF and R = 100 ohm in series, the resonance frequency in radian per second is
A resistor R, an inductor L and a capacitor C are connected in series to an oscillator of frequency n. If the resonant frequency is n r , then the current lags behind voltage when
If a bulb is connected first with DC and then AC of same voltage, then it will shine brightly
An AC supply gives 30 V which passes through a 10 Ω resistance. The power dissipated in it is
What will be the self-inductance of a coil to be connected in a series with a resistance of π 3 Ω such that the phase difference between the e.m.f. and the current at 50 Hz frequency is 30 0 ?
The potential difference V and the current i flowing through an instrument in an AC circuit of frequency/are given by V = 5 cos ( ωt ) volts and I = 2 sin ( ωt ) amperes (where ω = 2 πf ). The power dissipated in the instrument is
A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produces oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be
What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 μF and ω = 1000 s − 1 ?
In an AC circuit, the emf (e) and the current (i) at any instant are given respectively by e = E 0 sinωt i = I 0 sin ( ωt − ϕ ) The average power in the circuit over one cycle of AC is
A bulb is rated at 100V, 100W, it can be treated as a resistor. Find out the inductance of an inductor (called choke coil) that should be connected in series with the bulb to operate the bulb at its rated power with the help of an ac source of 200 v and 50 Hz.
In the given LCR circuit, what will be the respective readings of voltmeter and ammeter?
Which option contains the correct name for a series resonant RLC circuit ?
What can be said about two series resonant LCR circuits if same current flows through them when connected across a sinusodial voltage source?
In a series RLC circuit a high impedance AC voltmeter is used to measure the voltages across the inductor, the capacitor and the resistor. It is observed that the voltmeter gives the same reading (in V) for each element. Find this reading if a 100 V (RMS) AC source is used to drive the circuit.
Identify the incorrect option out of the following for the adjoining AC circuit.
The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitor. Then what is the value of capacitance?
A bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased, while keeping the voltage of the source constant, then
One 10 V, 60 W bulb is to be connected to 100 V line. The required induction coil has self inductance of value ( f = 50 Hz )
In the circuit given below, what will be the reading of the voltmeter
An LCR series circuit with a resistance of 100 ohm is connected to an ac source of 200 V (r.m.s.) and angular frequency 300 rad/s. When only the capacitor is removed, the current lags behind the voltage by 60 o . When only the inductor is removed the current leads the voltage by 60 o . The average power dissipated is
An alternating e.m.f. of angular frequency ω is applied across an inductance. The instantaneous power developed in the circuit has an angular frequency
The voltage of an ac source varies with time according to the equation V = 100 sin 100 πcos 100 πt where t is in seconds and V is in volts. Then
The diagram shows a capacitor C and a resistor R connected in series to an ac source. V 1 and V 2 are voltmeters and A is an ammeter Consider now the following statements I. Readings in A and V 2 are always in phase II. Reading in V 1 is ahead in phase with reading in V 2 III. Readings in A and V 1 are always in phase Which of these statements are/is correct
In the circuit shown in figure neglecting source resistance the voltmeter and ammeter reading will respectively, be
The voltage of an ac supply varies with time ( t ) as V = 120 sin 100 π tcos 100 π t . The maximum voltage and frequency respectively are
In the circuit shown in the figure, the ac source gives a voltage V = 20 cos ( 2000 t ) . Neglecting source resistance, the voltmeter and ammeter reading will be
In a certain circuit current changes with time according to i = 2 t . r.m.s. value of current between t = 2 s to t = 4 s will be
A telephone wire of length 200 km has a capacitance of 0.014 μ F per km. If it carries an ac of frequency 5 kHz, what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum
Match the following Currents r.m.s. values (a) x 0 sin ωt (i) x o (b) x 0 sin ωtcos ωt (ii) x 0 2 (c) x 0 sin ωt + x 0 cos ωt (iii) x 0 ( 2 2 ) (a) (b) (c) 1) i ii iii 2) ii iii i 3) i iii ii 4) None of these
The reading of ammeter in the circuit shown will be
In an A.C. circuit, containing an inductance and a capacitor in series, the current is found to be maximum when the value of the inductance is 0.5 henry and capacitance is 8 μF . The angular frequency of the input A.C. voltage must be equal to
The power factor of the circuit shown in fig.(24) is
In an A.C. circuit V and I are given by V = 100 sin ( 1000 t ) volt and I = 1000 sin ( 1000 t + π / 3 ) mA The power dissipated in the circuit is
The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an A.C. supply of 120 V and the current flowing in it is 10 A. The voltage and the current in the secondary are
A step-down transformer is connected to 2400 volt line and 80 ampere of current is found to flow in output load. The ratio of the turns in primary and secondary coil is 20 : 1. If transformer efficiency is 100%, then the current flowing in the primary coil will be
