Electromagnetic Induction and Alternating Currents — practice questions

87 curated practice questions from Electromagnetic Induction and Alternating Currents (Physics JEE Main, NTA Exams) — 73 easy, 8 medium, 6 hard. Every question includes the final answer free; step-by-step worked solutions with a free account.

In the circuit shown here, the point ‘C’ is kept connected to point ‘A’ till the current flowing through the circuit…
A coil of resistance 200 ohm and self inductance 1.0 henry has been connected to an a.c. source of frequency 200/π Hz…
A straight conductor of length 0.4 m is moved with a speed of 7 ms –1 perpendicular to a magnetic field of induction…
A magnet is moved towards a coil: rapidly slowly Then, the induced emf is
If a coil of 40 turns and area 4.0 cm 2 is suddenly removed from a magnetic field, it is observed that a charge of 2.0…
The flux linked with a coil at any instant t is given by φ = 10 t 2 – 50t + 250 The induced emf at t = 3 s is
A coil of inductance 8.4 mH and resistance 6Ω is connected to a 12V battery. The current in the coil is 1A at…
For the LR circuit shown in figure, the phase angle if frequency is 100/π is
A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one…
In L-C-R series A.C. circuit, the phase angle between current and voltage is
Two solenoids of same cross-sectional area have their lengths and number of turns in ratio of 1 : 2. The ratio of…
In a uniform magnetic field of induction B, a wire in the form of a semicircle of radius r rotates about the diameter…
The average power dissipation in a pure capacitor in AC circuit is
A series LCR circuit is tuned to resonance. The impedance of the circuit now is
A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field…
The alternating current I in an inductance coil varies with time according to graph given in figure Which one of the…
The magnetic flux linked with a circuit of resistance 100 ohm increases from 10 to 60 weber. The amount of induced…
The current passing through a choke coil of 5H is decreasing at the rate of 2 As –1 . The e.m.f. developed across the…
How much current will flow in a circuit having resistance of 109 Ω and an inductance of 0.5 H connected to an A.C…
The magnetic flux linked with a vector A in a uniform magnetic field E is:
A coil having 500 square loops each of side 10 cm is placed normal to a magnetic field which increased at a rate of 1.0…
A circuit consists of an inductance of 0.5 mH and a capacitor of 20 μF. The frequency of the LC oscillations is…
A coil having n turns and resistance R Ω is connected with a galvanometer of resistance 4R Ω. This combination is moved…
In electromagnetic induction, the induced e.m.f in a coil is independent from
An inductor (L = 100 mH) a resistor (R = 100Ω) and a battery (E = 100 V) are initially connected in series as shown in…
A cylindrical conducting rod is kept with its axis along the x - axis. Also there exists a uniform magnetic field…
What is the value of inductance L for which the current is a maximum in a series LCR circuit with C = 10 μF and ω =…
The inductance between A and D is
An alternating voltage E = 200 2 sin (100 t) volt is connected to a 1 µ F capacitor through an A.C. ammeter. The…
One conducting U-tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes…
A physicist works in a laboratory where the magnetic field is 2 T. She wears a necklace enclosing area 0.01 m 2 in such…
The potential difference V cd across the inductor L is
The coil of a dynamo has N turns, area A and it rotates with an angular velocity ω in a uniform magnetic field B. The…
A parallel plate capacitor has circular plates each of radius 5 cm. It is being charged so that electric field in the…
Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A = 10 cm 2 and…
In the series LCR circuit, the voltmeter and ammeter readings are :
A 60 volt–10 watt bulb is operated at 100 volt–60 Hz a.c. The inductance required is
Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross sectional area A = 10 cm 2 and…
As a result of change in the magnetic flux linked to the closed loop shown in the figure, an e.m.f. . V volt is induced…
A coil having 500 square loops of side 10 cm is placed normal to magnetic field which increases at a rate of 1 T/sec…
What is the self inductance of an air core solenoid 1 m long, diameter 0.5 m, if it has 500 turns ? Take π 2 = 10.
A long solenoid has 500 turns. When a current of 2 A is passed through it, the resulting magnetic flux linked with each…
A flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the…
Which of the following curves, figure correctly represent the variation of capacitive reactance (X C ) with frequency…
If a copper ring is moved quickly towards south pole of a powerful stationary bar magnet then
In an ac circuit, with voltage V and current I the power dissipated is
The instantaneous magnetic flux φ in a circuit is φ = 4t 2 – 4t + 1. The total resistance of circuit is 10 Ω. At t = 1…
The power factor of an a.c. circuit having resistance R and inductance L connected in series to an a.c. source of…
In an A.C. circuit, voltage applied is V = 220 sin 100 t. If the impedance is 110 Ω and phase difference between…
If number of turns in primary and secondary coils is increased to two times each, the mutual inductance
In general, in an alternating current circuit (for non-zero current)
In an a.c. circuit, V and I are given by V = 100 sin (100 t) volt I = 100 sin (100 t + π /3) mA. The power dissipated…
A thin semi-circular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction…
A small piece of metal wire is dragged across the gap between the poles of a magnet in 0.4 s. If change in magnetic…
In the circuit shown in figure the r.m.s. value of e is 5 V and r.m.s. value of voltage drop across L is 3 V. The…
For a series LCR circuit at resonance, the statement which is not true is
An ideal coil of 10 H is connected in series with a resistance of 5Ω and a battery of 5 V. 2 s after the connection is…
A conducting ring of radius r is rolling without slipping with a constant angular velocity ω in figure. If the magnetic…
An e.m.f. of 15V is applied in a circuit containing 5H inductance and 10Ω resistance. The ratio of the currents at time…
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A)…
A coil of 40 H inductance is connected in series with a resistance of 8 Ω and the combination is joined to the…
When magnetic flux through a coil is changed, the variation of induced current in the coil with time is as shown in…
The inductive reactance of a coil of 0.2 H inductance at a frequency of 60 Hz is
A loop of area 0.1 m 2 rotates with a speed of 60 rps perpendicular to a magnetic field of 0.4 T. If there are 100…
An electric bulb has a rated power of 50 W at 100 V. If it is used on an AC source 200 V, 50 Hz, a choke has to be used…
In an LR circuit, current falls to 19 times the initial value in a time T during the decay of current, then the value…
At resonance, in a series LCR circuit, which relation does not hold ?
The magnetic field in a coil of 100 turns and 40 cm 2 area is increased from 1 tesla to 6 tesla in 2 second. The…
When the current changes from +2 A to -2 A in 0.05 seconds, an e.m.f, of 8 V is induced in the coil. The coefficient of…
The current through a coil of self-inductance L = 2 mH is given by i = t 2 e -t at time t. How long it will take to…
One coil of resistance 40Ω is connected to a galvanometer of 160Ω resistance. The coil has radius 6mm and turns 100…
The ratio of the secondary to the primary turns in a transformer is 3 : 2 and the output power is P. Neglecting all…
A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power…
A coil of cross-sectional area 10 2 cm 2 is placed in the magnetic field, which changes by 4 × 10 –2 Wb/cm 2 within 5…
In a uniform magnetic field of induction B , a wire in the form of semicircle of radius r rotates about the diameter of…
In the given figure if the magnetic field, which is perpendicular to the plane of the paper in the inward direction…
The magnetic flux =3 t^ 2 +4 t+9 linked with the coil varies with time. The magnitude of the induced emf after 2 s is
The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux Ф linked…
A square frame of side 10 cm and a long straight wire carrying current 1 A are in the plane of the paper. Starting from…
For a coil having L = 2 mH, current flows at the rate of 10 3 ampere/sec. The emf induced is
Figure shows three regions of magnetic field, each of area A, and in each region magnitude of magnetic field decreases…
Two identical cycle wheels (geometrically) have different number of spokes connected from centre to rim. One is having…
According to Maxwell’s hypothesis, a changing electric field gives rise to
A coil of inductance 8.4 mH and resistance 6 Ω is connected to a 12 V battery. The current in the coil is 1.0 A at…
In series LR circuit, X L = 3 R. Now a capacitor with X C = R is added in series. The ratio of new to old power factor…
Two coils of self-inductances 2 mH and 8 mH are placed so close to each other that the effective flux in one coil is…
When the current changes from + 2 A to –2 A in 0.05 s, an emf of 8 V is induced in a coil. The coefficient of…

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