1

AIR PRACTICE SHEET (2025-26)

12th JEE Alternating Current [STANDARD]

Single Choice Correct Type Questions 4. An alternating voltage E = 200 2 sin (100t) is
1. The instantaneous voltages at three terminals marked connected to 1µF capacitor through an ideal ac
X, Y and Z are given by ammeter. The reading of the ammeter shall be:
Vx = V0 sin ωt
 2  (1) 10 mA (2) 20 mA
Vy = V0 sin  t +  and (3) 40 mA (4) 80 mA
 3 
 2  5. An alternating current source of frequency 100 Hz is
Vz = V0 sin  t + 
 3  joined to a combination of a resistance, a capacitance
An ideal voltmeter is configured to read rms value of and a coil in series. The potential difference across
the potential difference between its terminals. It is the coil, the resistance and the capacitor is 46, 8 and
connected between point X and Y and then between Y 40 volt respectively. The electromotive force of
alternating current source in volt is:
and Z. The reading (s) of the voltmeter will be
(1) 94 (2) 14
(3) 10 (4) 76
1
rms
(1) VYZ = V0
2 6. A capacitor C is charged to potential difference V0 at
3 t = 0. If is connected to LC circuit as shown. Switch
rms
(2) VXY = V0 S is closed at t = 0. Maximum current passing through
2
inductor, is:
(3) Depends on the choice of the two terminal
rms
(4) VXY = V0

2. Two alternating voltage generators produce emf of

the same amplitude E0 but with a phase difference of
π/3. The resultant emf is: (1) V0
2C
(2) V0
C

 t + (  / 3)
(1) E0 sin  3L 3L
C V C
 t + (  / 6)
(2) E0 sin  (3) V0 (4) 0
2L 2 L
(3) 3E0 sin ( t + (  / 3))
7. For the circuit shown in figure, current (I) through the
(4)  t + (  / 2)
3E0 sin  circuit is 5 sin (ωt + ϕ) A. At a particular instant
potential difference across capacitor is 24 V. Then the
3. When 100V DC is applied across a solenoid, a current potential difference across resistance at that instant, is
of 1 A flows in it. When 100V AC is applied across
the same coil, the current drops to 0.5A. If the
frequency of the AC source is 50 Hz, the impedance
and inductance of solenoids are:
(1) 100 Ω, 0.93 H (2) 200 Ω, 1.0 H
(1) 18V (2) 24 V
(3) 10 Ω, 0.86 H (4) 200Ω, 0.55 H
(3) 40 V (4) 30 V
 2

8. A choke coil has: One or More Than One Type Questions

(1) High inductance and low resistance 13. In the R-C circuit shown below.
(2) Low inductance and high resistance
(3) High inductance and high resistance
(4) Low inductance and low resistance

9. An LC circuit contains a 20 mH inductor and a 50µF

capacitor with an initial charge 10 mC. The resistance (1) The average power dissipated is 300 watt
of circuit is negligible. At this instant, the circuit is (2) The phase difference between the current in the
closed at t = 0. At what time is the energy stored in source and source voltage is π/4
the circuit is completely magnetic? 3
(1) t = 0 (2) t = 1.57 ms (3) The power factor of the circuit is
10
(3) t = 3.14 ms (4) 6= 6.28 ms
1
(4) The power factor of the circuit is
10. The impedance Z1 in figure can be regarded as a pure 2
resistance R1 = 12Ω, whereas the impedance Z2 is
associated with a series resistance R2 = 8Ω and a 14. A circuit shown consists of two identical coils each
capacitance C = 1µF. If f = 5000 Hz and v0 = 30 V, of inductance L, two identical capacitors each of the
what is the power dissipated in Z2 (in W)? Take π2 = capacitance C and a variable frequency alternating
10. voltage source. Find expression for the angular
frequency of the source at which the peak voltage
between the terminals A and B becomes η ≥ (1) time
of the peak volage of the source

(1) 2.57 (2) 3.12

(3) 257 (4) None of these

11. A circuit consisting of an inductance and a resistance

joined to a 200 volt supply (A.C.). It current of 10  −1 1
(1) If XC > XL then  = 
ampere. If the power used in the circuit is 500 watt.  + 1 LC
Calculate the wattless current.
 +1 1
10 7 7 7 (2) If XC < XL then  = 
(1) A (2) A  − 1 LC
4 4
5 7 9 7  −1 1
(3) A (4) A (3) If XC < XL then  = 
4 4  + 1 LC
1  +1 1
12. The power factor of the circuit in Figure is . The (4) If XC > XL then  = 
2  − 1 LC
capacitance of the circuit is equal to:
15. An inductor 4H and a resistance 5Ω are connected in
series with an AC source. At a particular instant,
voltage across inductor is 3 volt and across resistor is
4 volt. For that particular instant, choose correct
options :
(1) 400 µF (1) Voltage across source is 5 volt
(2) 300 µF (2) Voltage across source my be 7 volt
(3) 500 µF (3) Voltage across source may be 1 volt
(4) 200 µF (4) Current in circuit is 0.8 amp
 3

16. Two alike discharge lamps are operated from the

mains, 230 V and 50 Hz, and they are both connected
to inductors in series. The inductors are alike. A
condenser is connected in series to one of the
discharge tubes. With this arrangement it is ensured
that when the current through one of the lamps is
maximum, then the current through the other one is (1) f = 125 Hz
minimum and vice-versa. The average value of the (2) f = 250π Hz
power is 8W for each discharge lamp. Then which of (3) Current through R is 2A
the following is(are) correct? (Assume discharge (4) V1 = V2 = 1000 V
lamps as resistors)
(1) The value of resistance of discharge tube is 3.3 19. In an ac circuit shown below, voltage Vxy and Vyz are
kΩ 100 V each. If the main line current is 5A, then [All
(2) The capacitance of condenser is 6.6µF given value are RMS values]
(3) The total impedance of the discharge tube and
the inductor together is 4.67 kΩ
(4) The capacitive reactance is double of inductive
reactance.

17. Which of the following is/are correct for alternating

current circuit?
(1) Power consumed in circuit is 250 3 W
(2) The capacitor reactance of circuit will be 40Ω
(3) If Vsource = 100 2sin (100t ) , then current
5 3  
through resistor I R = sin 100t − 
2  3
(1) In LCR series circuit, current through R at (4) Current in capacitors C is lagging voltage VYZ by
resonance is maximum 30°.
(2) In the series LCR circuit, current is zero at
resonance 20. Figure shows a two branched parallel circuit with
(3) Alternating current measuring instruments 3 3
RA = 10, L = H , RB = 20 and C = mH .
should have a non-linear scale 10 2
(4) In an AC circuit, the applied rms voltage is not Current in L − RA is I1 and in C- RB is I2 and main
equal to algebraic sum of rms voltage across current is I.
series elements (1) Phase difference between I1 and I2 is 90°
(2) At some instant current in L- R2 is 10A. At the
18. For the figure shown, R = 100Ω, L =
2
H and same instant current in C − RB branch will be
 5 3A
8
C = F are connected in series with an AC source (3) At some instant I1 is 10 2A then at this instant

I will be 10 2A
200V and frequency f. V1 and V2 are two hot wire
voltmeters. If the reading of V1 and V2 are same, then: (4) At some instant I2 is 10 2A then at this instant
I will be 10 2A
 4

21. Choose the correct option regarding the following

A.C. circuit:

(1) Voltmeter reading, V1 = 0

(2) Voltmeter reading V2 = 0
(3) Voltmeter reading V3 = 0
1 (4) Voltmeter V4 reading = voltmeter V5 reading
(1) Resonance occurs  =
LC
(2) Resonance occurs when power factor is Integer Type Questions
24. A current of 6 A flows in a coil when connected to a
maximum
dc source of 18 V. If the same coil is connected to an
(3) Resonance occurs when reactive power of ac source of 20 V, 50 rad/s, a current of 4 A flows in
circuit becomes equal to zero the circuit. The inductance of the coil is 10x mH. Find
2 out the value of x.
1 R
(4) Resonance occurs when  = −
LC  L  25. In the circuit shown, reactance of each capacitor is
R
4R, and that of each inductor is . If R = 5Ω then
22. For a series LCR circuit given below, ω0 is the 3
find reading of ammeter (in amperes)
resonance frequency. Then (R = 12 Ω, ω0L = 6Ω and
operating angular frequency, ω is half of the

resonance frequency i.e.  = 0 )
2

26. A capacitor of capacitance 1µF is charged to potential

difference 2V and is connected to an inductor of 1
mH. At an instant when potential difference across.
4
(1) Power factor of the circuit is The capacitor is 1 V, the current in the circuit is
5
10 x
3 10−2 ampere. Find out the value of x.
(2) Power factor of the circuit is 3
5
53 27. Consider a circuit with an alternating source and
(3) Current lags voltage by phase of
180 contains inductor and capacitor. Given reading of A1
37 and A2 as 3 ampere and 5 respectively. Find the
(4) Current lags voltage by phase of reading of A in ampere.
180

23. A resistor R and inductor L, a capacitor C and

voltmeter are connected to an oscillator in the circuit
as shown in the figure. When the frequency of the
oscillator is increased up to resonance frequency,
then:
 5

28. When a device P is connected across a 220 V, 50 Hz V0

(1)
alternating supply the voltage leads current by π/3. 4
When a device Q is connected across the same supply V
(2) 0
the current leads voltage by π/6. The two devices 3
have same resistance and different reactance. These 5V0
two devices are connected in series with voltage V (3)
4
and current i lags the voltage by ϕ. If value of ϕ is (4) None of these
π/k then find k.
32. Potential difference across capacitor of capacitance C
29. For a series LCR circuit, at resonance frequency (ω0), when the current in the circuit is maximum is:
2
inductive reactance 0 L = R and P0 is the power
3 V0 3V0
(1) (2)
dissipated across the circuit. If now operating 4 4
frequency increased to ω =2ω0 and ‘P’ is the power 5V0
(3) (4) None of these
P 4
dissipation across the circuit, then find the ratio 0 .
P
33. The maximum current in the inductor is :
60
30. In the circuit shown, voltmeters across L and R V
2 3V 3C 3C
(1) (2) V0
20 2 L L
and V respectively. At an instant when voltage
2 3C C
(3) 2V0 (4) V0
across inductor is 128V, then the voltage across L L
resistor R is in V at that instant. Find the value of n.

Paragraph (34 to 36)

In a series L − R circuit, connected with a sinusoidal ac
source, the maximum potential difference across L and R
are respectively 3 volts and 4 volts.

34. At an instant the potential difference across resistor

Paragraph (31 to 33) is 2 volts. The potential difference in volt, across the
Two capacitors of capacitance C and 3C are charged to inductor at the same instant will be:
potential difference V0 and 2V0, respectively and connected (1) 3cos 30°
to an inductor of inductance L as shown in figure. Initially (2) 3cos 60°
the current in the inductor is zero. Now the switch S is (3) 3cos 45°
closed. (4) None of these
35. At the same instant, the magnitude of the potential
difference in volt, across the ac source may be :
4+3 3
(1) 4 + 3 3 (2)
2
3 3
(3) 1 + (4) 2+
2 2
31. Potential difference across capacitor of capacitance
3C when the current in the circuit is maximum is :
 6

36. If the current at this instant is decreasing the Column-I Column-II

magnitude of potential difference at that instant A 1 P I1 and I2 are in
If L1 − = R1 and
across the ac source is: C1 same phase
(1) Increasing
1
(2) Decreasing L2 − = R2
C2
(3) Constant
B 1 Q I = I1 + I2 (I, I1,
(4) Cannot be said If L1 − = R1 and
C1 I2 rms value of
Match the following Type Questions 1 currents)
− L2 = R2
37. A conducting loop is held in a uniform but time C2
varying magnetic field such that the field is C If capacitor is absent in 1 and R Phase
perpendicular to the plane of the loop. inductor is absent in 2 and difference
The magnetic field is varying time sinusoidal as 1 between I1 and
shown in figure. L1 = R1, = R2
C1 
I2 is
2
D If capacitor are not present in S I = I1 + I2 (I, I1,
both and L2 = R2 , L1 = R1 I2 rms value of
currents)

39. In column-I AC circuits are given and in column-II

Match the column I with column II variation of i with respect to ω is give. Match the
Column-I Column-II following. Value of R, L and C is constant and only
A Induced current is zero at P t1 ω of source is varied.
B Induced current is Q t2 Column-I Column-II
maximum a A.C. circuit i = f (ω)
C Average induced current R t3 A P
is zero from t = t1 to
D Average induced current S t4
is maximum from t = 0 to
T t5
B Q
38. An alternating LCR circuit is shown in figure, then
match the column:
C R

D S
 7

100 43. A voltage VAB = V0 cos ωt, where V0 is a real

40. For series R-L-C circuit, R = 100, C = F and
 amplitude, is applied between the point A and B in the
100 1
L= mH are connected to an AC source as shown network shown in figure. Given that C =
 R 3
in figure. The mass value of AC voltage is 220 V and
its frequency is 50 Hz. In Column I, some physical
quantities are mentioned while in column-II
information about quantities are provided. Match the
following columns and select the correct option from
the codes gives below.
(1) Calculate the total impedance between A and B.
(2) Verify that voltages of equal amplitude are
developed between the point X and the points A,
Y and Z.
(3) Determine the phases of these three voltages
Column-I Column-II relative to VAB.
A Average power P Zero
dissipated in the
44. Find the phase difference between i1 and i2 in the two
resistor is
branches of the circuit shown.
B Average power Q Non-zero
dissipated in the
inductor is
C Average power R 163 SI units
dissipated in the
capacitor is
D rms voltage across S 265.7 SI unit
the capacitor is
A B C D
(1) Q, S P P Q, R 45. An alternating voltage of 260 and ω = 100
(2) Q R R, S P radian/second, is applied in an LCR series circuit
(3) S, Q R P, Q S where L = 0.01H, C = 4 × 10–4 F and R = 10Ω. The
(4) P, Q R P, R S power supplied by the source is 200k. Find the value
of k.
41. A resistance (R), Inductance (L) and capacitance (C)
are connected in series to an ac source of voltage V 46. For an A.C. circuit shown in figure, show that the
having variable frequency. Calculate the energy 1 1 R2
delivered by the source to the circuit during one resonance frequency is given by f = − .
2 LC L2
period if the operating frequency is twice the
resonance frequency.

Subjective Type Questions

42. An AC source of angular frequency ω is fed across
resistor R and a capacitor C in series. The current
registered is i. If now the frequency of the 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.
 8

JEE Booster Questions (a) Which switch is closed? (S1, S2 or S3)

47. In the circuit shown the source voltage is given as v (b) Find the value of L and C.
= V0 sin ωt. Find the current through the source as a
function of time.

48. A series LCR circuit having resistance R, capacitance

C and inductance L has a voltage source of angular 51. A resistance R and a capacitor having capacitance C
frequency ω and voltage Vin. Output voltage (Vout) is are connected to an alternating source having emf v=
taken as voltage across the resistor and inductor 1
V0 sin (ωt). It is given that  =
combined. 3RC
V
(a) Find  = out (a) Plot the variation of power supplied by the
Vin source as a function of time. Mark the maximum
(b) Find η is the limit of large and minimum values of power in the graph.
 1 1 R (b) How does the plot change if capacitor is
  
RC LC L 
, , removed and only R remains connected to the

source?
(c) Find η in the limit of small (c) Plot the graph when only C remains connected
 1 1 R to source and R is removed.
  
RC LC L 
, ,


52. The circuit shown consists of seven identical coils

each of inductance L, one capacitor of capacitance C,
two batteries and two switches with a common
49. In a series LCR circuit, the frequency at which the handle shown by dashed double lines. The common
1 handle operates both the switches simultaneously.
current amplitude is times the current amplitude
2 Initially the switch is in position 1 for a long time and
at resonance are f1 and f2 (> f1). Find the frequency currents I1 and I2 are flowing in the coils. After the
bandwidth of resonance with is defined as Δf = f2 − switch is thrown to position 2, find the maximum
f1. Express your answer in terms of R and L. Assume charge acquired by the capacitor and corresponding
that resonance frequency f0 >> Δf. current in the right-most coil.

50. In the circuit shown in the figure, one of the three

switches is kept closed and other two are open. The
value of resistance is R = 20 Ω. When the angular
frequency (ω) of the 100V source is adjusted to 500
rad/s, 1000 rad/s and 2000 rad/s it was found that the
current I was 4A, 5A and 4A respectively.
 9

53. Two ideal inductors each of inductance L are

connected in series and then a capacitor of
capacitance C is connected in parallel to one of the
inductors. This combination is connected across a
series combination of an incandescent lamp and a
variable frequency alternating voltage source as
shown in the figure. It has been observed that the
lamp glows with minimum brightness at an angular
frequency ω. At what angular frequency will the
lamp glow with maximum brightness? 57. Let us consider the electric circuit in the figure, for
which L1 = 10mH, L2 = 20mH, C1 = 10 nF, C2 = 5
nF, R = 100 kΩ. The switch K being closed, the
circuit is coupled with a source of alternating current.
The current furnished by the source has constant
intensity while the frequency of the current may be
varied.

54. A circuit shown consists of two identical inductors,

two identical voltmeters A and B and a source of
alternating voltage u = V0 sin(2πft). The voltmeters
offer only resistances in the circuit. If the frequency
of the voltage source is changed over a wide range,
what maximum reading will the voltmeter B show?

(a) Find the ratio of frequency vM/Δv, where vm is

the frequency for which the active power in
circuit has the maximum value Pm, and the
frequency difference Δv = v+ − v−, where v+ and
v− are the frequencies for which the active power
55. Consider a network shown in the figure consisting of in the circuit is half of the maximum power
a resistance, a capacitor, an inductor and three
1
alternating voltage sources 1, 2 and 3. Terminal P = Pm .
2
voltages of the sources 1, 2 and 3 are u1, = V sin (ωt),
The switch is opened in the moment t0 when there is
v2 = Vsin (ωt +120°) and v3 = Vsin(<ωt+ 240°) no current through the resistor. Immediately after the
respectively and moduli of the reactances of the switch is open, the intensities of the currents in the
capacitor and the inductor are equal to the resistance. coils L1 and L2 are respectively i01 = 0.1 A and i02 =
Find the voltage of the junction P. 0.2A. (the currents flow as in the figure); at the same
moment, the potential difference on the capacitor
with capacity C1 is U0 = 40V.
(b) Calculate the frequency of electromagnetic
oscillation in L1C1C2L2 circuit;
(c) Determine the intensity of the electric current in
the AB conductor;
56. Find the natural frequencies of the circuit shown in (d) Calculate the amplitude of the oscillation of the
the figure. intensity of electric current in the coil L1.
 10

58. When sine waves propagate in an infinite LC-grid 61. In the circuit shown in the figure, the sinusoidal input
(see the figure below) the phase of the AC voltage voltage has a fixed amplitude V0 and frequency f.
across two successive capacitors differs by ϕ. What is the maximal amplitude of the output voltage,
(a) Determine how ϕ depends on ω, L and C (ω is and for which values of the variable resistances R1,
the angular frequency of the sine wave). R2, and R3 is the maximal amplitude achieved?
(b) Determine the velocity of propagation of the
waves if the length of each unit is l.
(c) State under what conditions the propagation
velocity of the waves is almost independent of
ω. Determine the velocity in this case.
(d) Suggest a simple mechanical model which is an
analogue to the above circuit and derive JEE Mains Previous Year Questions
equations which establish the validity of your 62. If R,XL , and X C represent resistance, inductive
model. reactance and capacitive reactance. Then which of the
following is dimensionless: [2023]
R
(A) (B) RXL XC
X L XC
59. A circuit consists of two identical inductances, two XL R
(C) R (D)
identical capacitors, and one resistor, see figure. The XC X L XC
applied voltage is U0 = 10V, and the total current at
the input leads is I0 = 1A; the voltage measured at the 63. An alternating voltage source V = 260sin(628t) is
left capacitor is 10V, and 10V is also measured at the connected across a pure inductor of 5mH . Inductive
left inductance. What is the active power dissipated
reactance in the circuit is :
in this circuit and what is the resistance of the
[2023]
resistor?
(A) 6.28 (B) 3.14
(C) 0.318 (D) 0.5

64. For the given figures, choose the correct options:

60. Determine all the natural frequencies of the circuit

shown in Figure. You may assume that all the
capacitors and inductances are ideal, and that the [2023]
following strong inequalities are satisfied: C1 ≪ C2, (A) The rms current in circuit (b) can never be larger
and L1 ≪ L2. Note that your answers need to be than that in (a)
simplified according to these strong inequalities. (B) The rms current in circuit (b) can be larger than
that in (a)
(C) At resonance, current in (b) is less than that in (a)
(D) The rms current in figure(a) is always equal to
that in figure (b)
 11

65. In the given circuit, rms value of current (Irms) through 69. Given below are two statements:
the resistor R is: 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 becomes zero.
In the light of the above statements, choose the
[2023] correct answer from the options given below:
(A) 2 A (B) 20 A [2022]
(A) Both Statement I and Statement II are true.
1
(C) A (D) 2 2 A (B) Both Statement I and Statement II are false.
2
(C) Statement I is true but Statement II in false.
(D) Statement I is false but Statement II is true.
66. In an LC oscillator, if values of inductance and
capacitance become twice and eight times, 70. A resistance of 40 Ω is connected to a source of
respectively, then the resonant frequency of oscillator alternating current rated 220 V, 50 Hz. Find the time
becomes x times its initial resonant frequency 0 . taken by the current to change from its maximum
The value of x is: [2023] value to rms value : [2022]
(A) 4 (B) 16 (A) 2.5 ms (B) 1.25 ms
(C) 1 / 4 (D) 1/16 (C) 2.5 s (D) 0.25 s

71. If wattless current flows in the AC circuit, then the

67. In a series LR circuit with XL = R , power factor is
circuit is: [2022]
P1 . If a capacitor of capacitance C with XC = XL is (A) Purely Resistive circuit
added to the circuit the power factor becomes P2 . (B) Purely Inductive circuit
(C) LCR series circuit
The ratio of P1 to P2 will be: [2023]
(D) RC series circuit only
(A) 1: 2 (B) 1 : 2
(C) 1 : 1 (D) 1 : 3 72. A sinusoidal voltage V(t) = 210 sin 3000t volt is
applied to a series LCR circuit in which L = 10 mH,
68. Match List I with List II: C = 25 μF and R = 100Ω. The phase difference (ϕ)
List I List II between the applied voltage and resultant current will
A. AC generator I. Presence of both L and be: [2022]
C (A) tan–1 (0.17) (B) tan–1 (9.46)
B. Transformer II. Electromagnetic (C) tan–1 (0.30) (D) tan–1 (13.33)
Induction
C. Resonance III. Quality factor 73. Two coils of self inductance L1 and L2 are connected
phenomenon in series combination having mutual inductance of
to occur the coils as M. The equivalent self inductance of the
D. Sharpness of IV. Mutual Induction combination will be: [2022]
resonance
Choose the correct answer from the options given
below: [2023]
(A) A-IV, B-II, C-I, D-III 1 1 1
(A) + + (B) L1 + L2 + M
(B) A-II, B-IV, C-I, D-III L1 L2 M
(C) A-IV, B-III, C-I, D-II (C) L1 + L2 + 2M (D) L1 + L2 – 2M
(D) A-II, B-I, C-III, D-IV
 12

74. The current flowing through an ac circuit is given by 78. The rms value of conduction current in a parallel
I = 5sin (120πt ) A plate capacitor is 6.9 μA. The capacity of this
capacitor, if it is connected to 230 V ac supply with
How long will the current take to reach the peak value
an angular frequency of 600 rad/s, will be:
starting from zero? [2022]
[2022]
1
(A) s (B) 60s (A) 5 pF (B) 50 pF
60 (C) 100 pF (D) 200 pF
1 1
(C) S (D) S
120 240 79. In a series LR circuit XL = R and power factor of the
circuit is P1. When capacitor with capacitance C such
75. For a series LCR circuit, I vs ω curve is shown:
that XL = XC is put in series, the power factor
(a) To the left of ωr, the circuit is mainly capacitive.
(b) To the left of ωr, the circuit is mainly inductive. P1
becomes P2. The ratio is: [2022]
(c) At ωr, impedance of the circuit is equal to the P2
resistance of the circuit. 1 1
(A) (B)
(d) At ωr, impedance of the circuit is 0. 2 2
3
(C) (D) 2 : 1
2

80. A series LCR circuit has L = 0.01 H, R = 10 Ω and C

= 1 μF and it is connected to ac voltage of amplitude
(Vm) 50 V. At frequency 60% lower than resonant
frequency, the amplitude of current will be
Choose the most appropriate answer from the options approximately: [2022]
given below: [2022] (A) 466 mA (B) 312 mA
(A) (a) and (d) only (B) (b) and (d) only (C) 238 mA (D) 196 mA
(C) (a) and (c) only (D) (b) and (c) only
81. To light, a 50 W, 100 V lamp is connected, in series
50
76. When you walk through a metal detector carrying a with a capacitor of capacitance μF with 200 V,
metal object in your pocket, it raises an alarm. This π x
phenomenon works on 50Hz AC source. The value of x will be __. [2022]
[2022]
(A) Electromagnetic induction 82. A circuit element X when connected to an a.c. supply
(B) Resonance in ac circuits of peak voltage 100 V gives a peak current of 5 A
(C) Mutual induction in ac circuits which is in phase with the voltage. A second element
(D) interference of electromagnetic waves Y when connected to the same a.c. supply also gives
the same value of peak current which lags behind the
77. To increase the resonant frequency in series LCR π
voltage by . If X and Y are connected in series to
circuit, [2022] 2
(A) Source frequency should be increased the same supply, what will be the rms value of the
(B) Another resistance should be added in series current in ampere? [2022]
with the first resistance. 10 5
(A) (B)
(C) Another capacitor should be added in series with 2 2
the first capacitor. 5
(D) The source frequency should be decreased. (C) 5 2 (D)
2
 13

83. The equation of current in a purely inductive circuit

is 5sin ( 49πt − 30) . If the inductance is 30 mH then
the equation for the voltage across the inductor, will
be: [2022]
 22 
Let π = 
 7
(A) 1.47sin ( 49πt − 30) 89. A series LCR circuit is connected to an ac source of
220 V,50 Hz . The circuit contain a resistance
(B) 1.47sin ( 49πt + 60)
R = 100 and an inductor of inductive reactance
(C) 23.1sin ( 49πt − 30) XL = 79.6 . The capacitance of the capacitor
(D) 23.1sin ( 49πt + 60) needed to maximize the average rate at which energy
is supplied will be_________ F .
84. An alternating emf E = 440 sin 100πt is applied to a Given 39.00
2
circuit containing an inductance of H. If an a.c. 90. An inductor of inductance 2H is connected in
π
ammeter is connected in the circuit, its reading will series with a resistance, a variable capacitor and an
be: [2022] AC source of frequency 7kHz . The value of
(A) 4.4 A (B) 1.55 A capacitance for which maximum current is drawn
(C) 2.2 A (D) 3.11 A 1
into the circuit is F , where the value of x
x
Integer Type Question is________ .
85. A series LCR circuit consists of 22
(Take  = )
R = 80,XL = 100 , and XC = 40 . The input 7
voltage is 2500 cos(100t)V . The amplitude of
current, in the circuit, is__________ A. 91. An inductor of 0.5mH , a capacitor of 20F and
resistance of 20 are connected in series with a
86. An LCR series circuit of capacitance 62.5nF and 220 V ac source. If the current is in phase with the
resistance of 50 , is connected to an A.C. source of emf, the amplitude of current of the circuit is xA.
frequency 2.0kHz . For maximum value of The value of x is –
amplitude of current in circuit, the value of
inductance is__________ mH . (Take 2 = 10) 92. As shown in the figure an inductor of inductance 200
87. A series LCR circuit is connected to an AC source mH is connected to an AC source of emf 220 V and
of 220 V,50 Hz . The circuit contains a resistance frequency 50 Hz. The instantaneous voltage of the
R = 80 , an inductor of inductive reactance a
source is 0 V when the peak value of current is A.
XL = 70 , and a capacitor of capacitive reactance π
x The value of a is _______. [2022]
XC = 130 . The power factor of circuit is . The
10
value of x is:

88. In the circuit shown in the figure, the ratio of the

quality factor and the band width is
 14

93. In a series LCR circuit, the inductance, capacitance

and resistance are L = 100mH, C = 100μF and R =
10Ω respectively. They are connected to an AC
source of voltage 220V and frequency of 50 Hz. The
approximate value of current in the circuit will
be____ A. [2022]
98. A telegraph line of length l00 km has a capacity of
0.01 µF/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 series is ________ mH. (if π =
10 ) [2022]
94. A 10W, 20 mH coil carrying constant current is
connected to a battery of 20 V through a switch is
99. In the given circuit, the magnitude of VL and VC are
opened current becomes zero in 100μs. The average
emf induced in the coil is ______ V. [2022] twice that of VR. Given that f = 50 Hz, the inductance
1
of the coil is mH. The value of K is ______.
95. A 110 V, 50 Hz, AC source is connected in the circuit Kπ
(as shown in figure). The current through the [2022]
resistance 55 Ω, at resonance in the circuit, will be
_______ A. [2022]

100. An inductor of 0.5 mH, a capacitor of 200 μF and a

resistor of 2 Ω are connected in series with a 220 V
96. A 220 V, 50 Hz AC source is connected to a 25 V, 5 ac source. If the current is in phase with the emf, the
W lamp and an additional resistance R in series (as frequency of ac source will be___× 102 Hz.
shown in figure) to run the lamp at its peak [2022]
brightness, then the value of R (in ohm) will be
______. [2022] 101. The effective current I in the given circuit at very high
frequencies will be ____A. [2022]

102. A capacitor of capacitance 500 μF is charged

97. An AC source is connected to an inductance of
100 mH, a capacitance of 100 µF and a resistance of completely using a dc supply of 100 V. It is now
120 Ω as shown in figure. The time in which the connected to an inductor of inductance 50 mH to
resistance having a thermal capacity 2 J°/C will get form an LC circuit. The maximum current in LC
heated by 16°C is ____s. circuit will be ______ A. [2022]
[2022]
 15

JEE Advance Previous Year Questions (1) I RA  I RB (2) I RA  I RB

103. You are given many resistances, capacitors and
inductors. These are connected to a variable DC (3) ICA  ICB (4) ICA  ICB
voltage source (the first two circuits) or an AC
voltage source of 50 Hz frequency (the next three 105. A long circular tube of length 10 m and radius 0.3m
circuits) in different ways as shown in Column II. carries a current I along its current surface as shown.
When a current I (steady state for DC or rms for AC) A wire-loop of resistance 0.005 ohm and of radius 0.1
flows through the circuit, the corresponding voltage m is placed inside the tube with its axis coinciding
V1 and V2 (indicated in circuits) are related as shown with the axis of the tube. The current varies as I = I0
in Column I. Match the two [IIT JEE-2010] cos(300t) where I0 is constant. If the magnetic
moment of the loop is Nµ0I0 sin (300t), then ‘N’ is
Column–I Column–II [IIT JEE- 2011]
A I  0, V1 is P
proportion
al to I

B I  0, V2 > Q
V1
106. A series R-C combination is connected to an AC
voltage of angular frequency ω = 500 radian/s. If the
impedance of the R-C circuit is R 1.25, the time
C V1 = 0, V2 = R constant (in millisecond) of the circuit is
V [IIT JEE- 2011]
107. In the given circuit, the AC source have w = 100 rad/s.
Considering the inductor and capacitor to be ideal,
the correct choice (s) is (are)
D I  0, V2 is S
proportion
al to I

T (1) The current through the circuit, I is 0.3 A.

(2) The current through the circuit, I is 0.3 2A
(3) The voltage across 100Ω resistor = 10 2V
(4) The voltage across 50Ω resistor = 10V

Paragraph
104. A series R-C circuit is connected to AC voltage A thermal power plant produces electric power of 600 kW
and 4000 V, which is to be transported to a place 20 km
source. Consider two cases ; (A) when C is without a
away from the power plant for consumers' usage. It can be
dielectric medium and (B) when C is filled with
transported either directly with a cable of large current
dielectric of constant 4. The current IR through the
carrying capacity or by using a combination of step-up and
resistor and voltage VC across the capacitor are
step-down transformers at the two ends. The drawback of
compared in the two cases. Which of the following the direct transmission is the large energy dissipation. In the
is/are true? [IIT JEE-2011] method using transformers, the dissipation is much smaller.
 16

In this method, a step-up transformer is used at the plant side (3) Immediately after A is connected to D, the
so that the current is reduced to a smaller value. At the current in R is 10 A.
consumers' end, a step-down transformer is used to supply (4) Q = 2 × 10−3C
power to the consumers at the specified lower voltage. It is
reasonable to assume that the power cable is purely resistive 111. In the circuit shown L = 1µH, C = 1µF and R = 1 kΩ.
and the transformers are ideal with a power factor unity. All They are connected in series with an A.C. source V =
the currents and voltages mentioned are rms values. V0 sin ωt as shown. Which of the following options
[IIT JEE -2013] is /are correct [IIT JEE 2017 (P-1)]

108. In the method using the transformers, assume that the

ratio of the number of turns in the primary to that in
the secondary in the step-up transformer is 1 : 10. If
the power to the consumers has to be supplied at 200
V, the ratio of the number of turns in the primary to
that in the secondary in the step-down transformer is
(1) The frequency at which the current will be in
(1) 200 : 1 (2) 150 : 1
phase with the voltage is independent of R
(3) 100 : 1 (4) 50 : 1
(2) At ω ~ 0 the current flowing through the circuit
becomes nearly zero
109. If the direct transmission method with a cable of
(3) At ω >> 106 rad s–1. the circuit behaves like a
resistance 0.4 Ω km–1 is used, the power dissipation
capacitor
(in %) during transmission is
(4) The current will be in phase with the voltage if
(1) 20 (2) 30
(3) 40 (4) 50 ω = 104 rad s–1

110. At time t = 0, terminal A in the circuit shown in the 112. The instantaneous voltages at three terminals marked
figure is connected to B by a key and an alternating X, Y and Z are given by [IIT JEE 2017 (P-2)]
current I (t) = I0 cos (ωt), with I0 = 1A and ω = 500 Vx = V0 sin t,
rad/s starts flowing in it with the initial direction  2 
VY = V0 sin  t +  and
7  3 
shown in the figure. At t = , the key is switched
6  4 
VZ = V0 sin  t + 
from B to D. Now onwards only A and D are  3 
connected. A total charge Q flows from the battery to An ideal voltmeter is configured to read rms value of
charge the capacitor fully. If C = 20µF, R = 10Ω and the potential difference between terminals. It is
the battery is ideal with emf of 50V, identify the connected between points X and Y and then between
correct statement(s): [IIT JEE- 2014] Y and Z. The reading(s) of the voltmeter will be
3
(1) VXYrms
= V0
2
1
(2) VXZrms
= V0
2
rms
(3) VXZ = V0
(1) Magnitude of the maximum charge on the (4) Independent of the choice of the terminals
7
capacitor before t = is 1 × 10−3C
6
(2) The current in the left part of the circuit just
7
before t = is clockwise.
6
 17

ANSWER KEY
1. (3) 3
2. (1) 42. ( )
5
3. (3)
 V0 
 3R,VAX = 3 ( 0)  , VYX = 30 ( −120)VZX = 30 (120)
43. V V
4. (3)
5. (2)  
6. (1) 44. (90°)
7. (2) 45. (5)
8. (1)  1 R 2 
46. f = 1 −
9. (2)  2 LC L2 
10. (2)  
11. (2) 1  1  
47. ( i = V0  sin t +  C −  cos t  )
12. (4) R  L  
13. (1, 3, 4) 2
 L 
14. (1, 3, 4) 1 + 
15. (1, 4) 48. (a)  R 
2
 L 1 
16. (2, 4) 1 + − 
17. (1, 2)  R RC 
18. (1, 3, 4) (b) 1
19. (1, 2, 4) (c) ωRC
20 (1, 2)
R
21. (2, 3, 4) 49. ( f = )
22. (1, 3) 2L
23. (2, 3, 4) 50. (a) S1
(b) L = 100 mH, C = 100 µF
24. (8)
25. (2)
26. (9)
27. (2)
28. (6) 51. (a)
29. (4)
30. (72)
31. (3)
32. (3)
33. (1)
34. (1)
35. (2)
36. (4)
37. (A(p, r), B(p, q, r), C(p, q, r), D(p, q, r)) (b)
38. (A(p, q), B(r, s), C(r, s), D(p, q))
39. (A(S), B(R), C(P), D(Q))
40. (1)
  (c)
 R LCV 2 
41. (E = )
  L 
 R + 2.25   
2
 C
 18

LC I +I 76. (2)
52. ( ( I1 +I 2 ) and 1 2 ) 77. (3)
7 7
78. (2)
53. ( 2 )
79. (2)
1 80. (3)
54. ( V0 )
3 81. (3)
55. ( )
( V 1 + 3 sin t ) 82. (4)
83. (4)
1 1 1
56. ( 1 = , 2 = , 3 = ) 84. (3)
LC 4 4 85. (25)
LC LC
3 7 86. (18)
C 1 LL 87. (8)
57. (R ; with L = 1 2 and C = C1 + C2; 88. (1)
L LC L1 + L2
89. (40)
0.1 A; 0.2A)
1  l 90. (3872)
58. (  = 2arcsin   LC  ; ;   1 when
2   91. (242)
l 92. (242)
v0 = ; infinite chain of masses
LC 93. (22)
connected by springs) 94. (400)
59. (10W, 30Ω) 95. (0)
2 5 1 96. (975)
60. ( 0; ; )
L2C2 2 L1C1 97. (15)
98. (100)
61. (V0; R1 = R2 = 0, R3 = L/Cr.)
99. (0)
62. (4)
100. (5)
63. (2)
64. (1) 101. (44)
65. (1) 102. (10)
66. (3) 103. (2)
67. (1) 104. (2)
68. (2) 105. (3)
69. (3) 106. (1)
70. (1) 107. (1)
108. (2)
71. (2) 109. (3)
72. (1) 110. (1)
73. (4) 111. (BONUS) at no option is correct, phase diff 
74. (4) 150°
112. (4)
75. (3)

PW Web/App - https://smart.link/7wwosivoicgd4

Library- https://smart.link/sdfez8ejd80if