AC Circuits Questions and Answers

In a series LCR circuit when an alternating voltage of peak value 500 V angular frequency 100 rad s is applied the peak voltage drops across L C and R can be respectively 0 200 V 300 V 0 800 V 500 V 400 V 600 V 200 V 300 V 1200 V 1600 V 300 V

4 none of these 2 An applied voltage signal consists of a superposition of a d c voltage and an a c voltage of high frequency The circuit consists of an inductor and a capacitor in series then 1 d c signal will appear across L and C 2 d c signal will appear across C and a c signal across L 3 d c signal will appear across L and a c signal across C across L and C a c signal will appears 3 racht 4 3 faya fa 1 2 3 4 LACT C uchra L LA

1 and 2 14 Figure shows the variation of i with oo in a m 1 0 in A 0 5 0 0 FG 11 00 0 5 1 0 1 5 rad s 1 R L C circuit 3 R C circuit 2 0 2 R L circuit 4 None of these

Same current is flowing in two alternating 2 circuits The first circuit contains only inductance and the other circuit contains only a capacitance If the frequency of the e m f of A C is increased the effect on the value of the current will be 1 increase in the first circuit and decrease in the other 2 increased in both circuits 3 decrease in both circuits 4 decrease in the first circuit and increase in the other Non resonant circuit what will be the nature of

A circuit is made up of resistance 3 0 and inductance 0 01 H An alternating emf of 100 V at 50 Hz is connected then the phase difference between the current and the emf in the circuit is tan tan tan 76 3 TE 7 2

46 In a series resonant LCR circuit the voltage across R is 100V and R 1KQ2 with C 2 F The resonant frequency is 200 rad s At resonance the voltage across L is 1 2 5 x 10 V 2 40 V 3 250 V 4 4 x 10 V

In RLC circuit at a frequency v the potential difference across each device are AVR max 8 8V AVL max 2 6V and AVC max 7 4V The composed potential difference AVC AVL max across inductor and capacitor is ONO No 10 0 V 7 8 V 7 4V

7 An alternating voltage V Vo sin oot is applied across a circuit As a result a current i io si cot flows in it The power consumed pe cycle is 1 zero 3 0 707 Voio 2 0 5 Voio 4 1 414 Voio

Figure shows LCR series ac circuit If L is removed from the circuit current leads voltage by 45 while if C removed current lags the voltage by 45 Current passing in the original circuit is R L wwwww HH Options 0 2 A O 1 5 A O 1 A O 0 5 A 1000 100V 200 Hz

An electric lamp designed for operation on 10V AC is connected to a 220V AC supply through a choke coil of inductance 2H for proper operation The angular frequency of the AC is 100 10rad s If a capacitor is to be used in place of the choke coil its cpacitance must be ONO 1 F

mA c 200 mA b 100 mA d 20 mA C B S E P M T 2011 A12 An AC voltage is applied to a resistance R and an inductor L in series IfR and the inductive reactance are both equal to 32 the phase difference between 102 the applied voltage and the current in the circuit

20 If a semiconductor has an intrinsic carrier concentration of 1 41 x 10 6 m3 when doped with 1021 m3 phosphorus then the concentration of holes at room temperature will be 1 2 10 1 3 1 41 10 0 2 2 10 1 4 1 41 10 6

7 An alternating voltage in volts given by V 200 2 sin 100t is connected to 1 F capacitor through an ideal a c ammeter in series The reading of the ammeter and the average power consumed in the circuit shall be

In the circuit shown in figure neglecting source resistance the voltmeter and ammeter reading will respectively be V X 10 22 ooowooo 1 OV 3A 2 150V 3A 3 150V 6A wwww X 10 2 400 320V A

A is false and R is also false 7 Assertion A The voltage sensitivity may not necessarily increase on increasing the current sensitivity Reason R Current sensitivity increases on increasing the number of turns of the coil 1 Point 0 0 Both A and R are true and R is the correct explanation of A Both A and R are true but R is not the correct explanation of A A is true but R is false A is false and R is also false

A bulb and an inductor are connected in series to an ac source through a switch The bulb glows with certain brightness when the switch is closed If a soft ferromagnetic material with large permeability is introduced into the inductor coil the brightness of the bulb will A decrease B increase C remain the same bogomor

An LCR series circuit connected across a source of alternating emf E is in resonance Then the voltage across 1 R is zero 2 R equals to applied voltage zero 3 C is zero 4 Lequals to applied voltage

10 If one of the i p of studied comparator is connected to 1Vdc other i p voltage is varied around this 1Vdc continuously Then the o p waveform of comparator is 2 Points sine wave Traingle wave Square wave can not predict

Cross a 230 V supply terminals in a house an electric iron having a resistance of 500 and incandescent lamp of resistances 450 d 800 respectively are connected For this operation exhibit the total current involved and also find the power taken from the pply mains

12 In a transformer primary voltage is 220V and secondary current is 0 11A with output power 60W 1 Transformer is step up 3 Transformer is auxiliary Ans 1 Sol P V x Is 60 V X 0 11 V 60 6000 0 11 11 220V V V Vp 220 volt so it is sten un transformer P S 0 11A 60 watt 2 Transformer is step down 4 None of these

Unleashing Potential In the circuit shown in figure input source is periodic and its wave form is 18 Find the reading of cathode ray oscilloscope CRO is R www Sol 1 3 Ans 4 t 1 1 t t3 2 t4 CRO t Relide INSTITUTE 8

R At resonance the applied voltage is Q times voltage drop across inductance for capacitance A If a current has both ac and dc components then a dc ammeter used to measure this current will measure the average value of the total current R The scale of dc ammeter is not uniformly divided over a long distance at F 5

162 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 TT If instead C is removed from the circuit 3 is the phase difference is again between current 3 and voltage The power factor of the circuit is 1 zero 2 0 5 31 0 Vik

3 A sinusoidal ac current passes through a resitor o resistance R in LCR series circuit If phase difference between supplied voltange and supplied current is and peak value of supplied current is I then power dissipated in the ckt is 1 IR cose 3 IR 2 4 IR 2 IR cos 0

PARAGRAPH FOR QUESTIONS 62 64 A box contains a combination of L C and R When 250 V DC is applied to the terminals of the box a current of 1A flows in the circuit When an AC source of 250 V at 2250 rad s 1 is connected a current of 1 25 A flows in the circuit When frequency of AC is increased it is observed that current increases with frequency and becomes maximum at 4500 rad s

In the circuit shown the power factor of the circuit is Power factor of only RC circuit is Source RMS voltage is 100 volt and its angular frequency w 100 4 5 rad sec RMS current in circuit is 5A If inductive reactance is greater then capacitive reactance then the value of self inductance Lis C H1 L wwww V 100 volt 100 rad sec R wwwwww

46 Mass of proton 1 67 MG0275 A circular coil placed in a uniform magnetic field If alternating current flows through this coil then 1 net force will act on coil 2 coil will be stationary 3 coil will be rotated 4 coil will move on straight line MG0276 50 2 3 4 A

The network shown in figure is a part of the circuit At a certain instant the current is 1 2 A and it is increasing at the rate of 10 A s The potential difference between he points A and B VA Ve is n volts Find n R 20 E 12V L 5mH B WWW 80000 A 2A 26 31 36

A circuit consists of a resistor of 50 a capacitor of 1 F and an ideal self inductor of 0 01H All three are in series with a power supply that generates an EMF of 10 sin cot volt The internal resistance of the power supply is negligibly small The system is at resonance We decreases the frequency of the power supply such that the reactance becomes 592 What will be average power generated by the power supply 1 10 W 2 5 W 3 15 W 4 Zero AVRE

A current flowing through the inductor of inductance L has a shape indicated in Fig The highest value of current is lo What will be the maximum voltage drop across the inductor O O zero 2T Llo 2T lo 0

a series ac circuit the instantaneous voltage e t and current i t are given b 5 cos wt 3 sin wt 5 sin wt 7 amp Then circuit is in resonance circuit is Inductive circuit is capacitive Information insufficient

For a series LCR circuit given below resonance frequency Then R 12 2 2 and operating angular frequency is half of is the L 6 000 the resonance frequency i e 00 2 R L mm 11 C vo o 1 Power factor of the circuit is 2 Power factor of the circuit is 4 5535 3 Current lags voltage by phase of 53 T 180 37 T

The value of a a and 3 are current gain in CB CE configuration Question Type Single Correct Type 2 a B G 3 1 is equal to None of these

An inductor is to be connected to the terminals of a generator rms voltage 11 0 V such that the resulting rms current is to be 0 710 A Determine the required inductive reactance Number Irms L 0000 Vrms

3 Choose the correct equation of current in the List Il as a function of t through the circuit elem ab of the circuits in the List 1 List 1 List II P O R S 10V A B 30V 1 10V Codes 30V P 3 3 202 www 202 20 202 www 202 www 2Q www www a Q 100 F b 292 www a breeeeee a b 20 www 0 4 mH eeeeee b 200 3 F a 0 6 mH b 0133 R411 S214 1 2 3 4 i 5A 1 e i 5A 1 e i 5A e 2 10 sec i 5A e 4 10 sec 1 2 10 sec 4 10 sec

Network shown in the diagram is part of an electrical circuit The current is 2 A and is decreasing of 2 Als then V V equals 1 2 V XVM M P 2 V 19 www 2 A 1 H 0000000 2 2 V 4 4 V

39 With an ac input from 50 Hz power line the ripple frequency is a 50 Hz in the dc output of half wave as well as full wave rectifier b 100 Hz in the dc output of half wave as well as full wave rectifier c 50 Hz in the dc output of half wave and 100 Hz in dc output of full wave rectifier d 100 Hz in the dc output of half wave and 50 Hz in the dc output of full wave rectifier In a full wave iunction diode rectifior th d input 14 8 Spe op Dio 44 What h diode a Th C b T

3 45 Initially the switch is in position 1 for a long time in the circuit shown in figure 3 397 At t 0 the switch is moved from 1 to 2 Obtain expressions for Vand VR for t 0 S THI 24 50V Figure 3 397 Ans V 50 3e 200 1 VR 150e 200r 5kn 1 F

The circuit consists of a capacitor connected in parallel to a resistor R with a coil of inductance L in series with them The power source could be an AC or a constant voltage DC source When AC source is applied then XL Xc R L vooroo C R If a constant DC source of voltage Eo is applied across the input terminal with a switch then Question Type Multiple Correct Type 1 Just after the switch is closed the initial current through the voltage source will be zero 2 Just after the switch is closed the initial current through the voltage source So will be R 3 The current through the voltage source long time after the switch is closed will be zero

The power dissipated in the following circuit will be about half of its maximum value at approximately 1H 100 Q 50 sinof 1 w 1050 rad s 2 w 1000 rad s 3 W 950 rad s 4 Both 1 3

20 A resistance of 4 92 and a wire of length 5 and resistance 52 are joined in series and connected to a cell of e m f 10 V and internal resistance 1 2 A Parallel combination of two identical cells is balanced across 300 cm length of the wire The e m f E of each cell is 1 1 5 V 452 ww 3 m E Fo Jor 10 V 1 Q 50 5 m 2 3 0 V

2 The number of turns in the primary and 41 secondary coils of a transformer are 5 and 10 respectively The mutual inductance is 25 H If the number of turns in the primary and secondary coils are changed to 10 and 5 respectively then the mutual inductance in henry will be 1 6 25 3 25 2 12 5 4 50 Bol Stara 25 ta af f aparat 1 6 25 3 25 af afde and ges 2 12 5 4 50

SolveLancer Test A student has a coil with resistance 20 and inductance 80 mH which is connected with a 10 V battery He obtains a steady state value of the current The time to acquire half of its steady state value is SolveLancer Test a b c d a b C 2 8 ms 3 5 ms 1 4 ms 5 6 ms

A perfect capacito nected in parallel to a variable frequency sinusoi dal alternating voltage supply At resonance the impedance of the circuit is 1 Lw 3 zero 2 4 1 Co infinite wz

ying straight i A rod of erpendicular city v then field variable with time as B Bot induced in the ring if the magnetic field is perpendicular to plane of loop is 1 mor 2 nar 3 2 4 n r The value of self inductance of a small circular col of radius r and number of turns n is 1 n r 2 Hon 2 4 Hon rr 4 wo colls A and Bha respectively are placed ne a current of 3A in A 104 Wb and with mutual inductance is 1 4 x 105 H 3 2 10 5 H 19 The primary ar have 60 and magnetic flus Hon r 3 14 n the circuit shown in the following figure E 10V R 292 R 392 R 692 and L 5H The current i just after pressing the switch S is wwwwwww R YR by do voltage ac Po are in 1 120 22 20 A tra lam A

31 The reactance of a capacitor is 2 ohm and that of an inductor is 3 ohm 1 poin If they are connected in series with a resistor of 1 732 ohm the angle of phase with which voltage ma lead the current is OA 0 degree B 30 degree OC 45 degree O D 90 degree

14012 In the circuit shown the variable resistance is so 32 adjusted that the ammeter reading is same in both the position 1 and 2 of the key The reading of ammeter is 2A If E 10V then x is His E Ideal 1 20 2 502 3 100 R TEST SERIES JOINT PACKAGE COURSE 4 200 3 1180 vakia fa ukanda 2A1E 10V Hw 1 20 Ideal 2 50 4 140 0 E 12fefani X 3 1002 4 2002 09990MD31032000

2 A series circuit of R 14 4 Ohm L 0 127H draws a current of 4 6 amp when connected to an alternating voltage source of 230V Find frequency of supply in Hz calculate active power reactive power and apparent power

a 1 5x103 V A 20 Henry inductor coil is connected to a 10 ohm resistance in series as shown in figure The time at which rate of dissipation of energy joule s heat across resistance equal to the rate at which magnetic energy is stored in the JEE Main 2019 inductor is E 2 In 2 c 2 In 2 a i 10 Q2 ww moooooo 20 H b In 2 d In 2 and IN 201 cross section arma A C

13 180 An AC circuit having supply voltage V consists of resistor of resistance 4 Q and capacitor of reactance 3 Q as shown in the figure The voltage across the capacitor at time t B Xc R www V 20 sin of 9 6 V 12 4 V Zero sis