NEET
Physics
Electromagnetic Induction and Alternating Current
Previous Years Questions

A closely packed coil having 1000 turns has an average radius of 62.8 cm. If current carried by the wire of the coil is 1 A, the value of magnetic fie...
Given below are two statements Statement I : In an a.c circuit, the current through a capacitor leads the voltage across it. Statement II : In a.c cir...
An inductor of inductance 2 mH is connected to a 220 V, 50 Hz ac source. Let the inductive reactance in the circuit is X1. If a 220 V dc source replac...
A standard filament lamp consumes 100 W when connected to 200 V ac mains supply. The peak current through the bulb will be :
The magnetic flux linked to a circular coil of radius R is $$\phi = 2{t^3} + 4{t^2} + 2t + 5$$ Wb The magnitude of induced emf in the coil at t = 5 s...
The peak voltage of the ac source is equal to
The energy that will be ideally radiated by a 100 kW transmitter in 1 hour is
A series LCR circuit with inductance 10 H, capacitance 10 $$\mu$$F, resistance 50 $$\Omega$$ is connected to an ac source of voltage, V = 200sin(100t)...
An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance 'R' are connected in series to an ac source of potential differ...
A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44W lamp. Ignoring power losses in the transformer, what ...
A series LCR circuit containing 5.0 H inductor, 80$$\mu$$F capacitor and 40$$\Omega$$ resistor is connected to 230V variable frequency ac source. The ...
Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance ...
A 40 $$\mu$$F capacitor is connected to a 200 V. 50 Hz ac supply. The rms value of the current on the circuit is, nearly :
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 $${... A 800 turn coil of effective area 0.05 m2 is kept. perpendicular to a magnetic filed 5 × 10–5 T. When the plane of the coil is rotated by 90o around ... In which of the following devices, the eddy current effect is not used? The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance An inductor 20 mH, a capacitor 100$$\mu $$F and a resistor 50$$\Omega $$are connected in series across a source of emf, V = 10 sin 314 t. The power... A long solenoid of diameter 0.1 m has 2$$ \times $$104 turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is plac... Figure shows a circuit that contains three identical resistors with resistance R = 9.0$$\Omega $$each, two identical inductors with inductance$$L$$... Which of the following combinations should be selected for better tuning of an L-C-R circuit used for combination ? A uniform magnetic field is restricted within a region of rafius r. The magnetic field changes with time at a rate$${{d\overrightarrow B } \over {dt}...
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 facto...
A small signal voltage V(t) = V0 sin$$\omega$$t is applied across an ideal capacitor C
A long solenoid has 1000 turns. When a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4 $$\times \,{10^{... An inductor 20 mH, a capacitor 50$$\mu F$$and a resistor 40$$\Omega $$are connected in series across a source of emf V = 10 sin 340t. The power lo... A series R-C circuit is connected to an alternating voltage source. Consider two situations : (a) When capacitor is air filled. (b) ... An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if ... A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance... A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure. T... A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the ... The primary of a transformer when connected to a dc battery of 10 Volt draws a current of 1 mA. The number of turns of the primary and secondary windi... A current of 2.5 A flows through a coil of inductance 5 H. The magnetic flux linked with the coil is A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when The instantaneous values of alternating current and voltage in a circuit are given as$$i = {1 \over {\sqrt 2 }}$$sin (100$$\pi $$t) ampere$$e = {...
In a coil of resistance 10 $$\Omega$$, the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. ...
A coil of resistance 400 $$\Omega$$ is placed in a magnetic field. If the magnetic flux $$\phi$$ (Wb) linked with the coil varies with time t (sec) ...
The current $$(I)$$ in the inductance is varying with time according to the plot shown in figure. Which one of the following is the correct variation...
In an electrical circuit R, L, C and a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between...
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, th...
The r.m.s. value of potential difference V shown in the figure is ...
An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3 $$\Omega$$, the phase d...
In the ac circuit an alternating voltage e = $$200\sqrt 2$$sin100t volts is connected to a capacitor of capacity 1 $$\mu$$F. The r.m.s. value of th...
The current $$i$$ in a coil varies with time as shown in the figure. The variation of induced emf with time would be ...
A condenser of capacity C is charged to a potential difference of V1. The plates of th condenser are then connected to an ideal inductor of inductance...
A conducting circular loop is placed in a uniform magnetic field, B = 0.025 T with its plane perpendicular to the loop. The radius of the loop is made...
A 220 volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is ...
In the given circuit the reading of voltmeter V1 and V2 are 300 volts each. The reading of the voltmeter V3 and ammeter A are respectively ...
A rectangular, a square, a circular and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with a constant velocit...
Power dissipated in an LCR series circuit connected to an A.C. source of emf $$\varepsilon$$ is
A conducting circular loop is placed in a uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop sta...
A long solenoid has 500 turns. When a current of 2 ampere is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4...
In an a.c. circuit the e.m.f. ($$\varepsilon$$) and the current (i)  at any instant are given respectively by $$\varepsilon$$ = E0sin$$\... A circular disc of radius 0.2 meter is placed in a uniform magnetic field of induction$${1 \over \pi }\left( {{{Wb} \over {{m^2}}}} \right)$$in such... The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux$$\phi $$linked with the primary coil is g... What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10$$\mu $$F and$$\omega $$= 1000 s$$-$$1 ? ... A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 amp, the efficiency of the transformer is approxi... Two coils of self inductance 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The m... A coil of inductive reactance 31$$\Omega $$has a resistance of 8$$\Omega $$. It is placed in series with a condenser of capacitative reactance 25 ... The core of a transformer is laminated because A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of fre... As a result of change in the magnetic flux linked to the closed loop as shown in the figure, an e.m.f.$$V$$volt is induced in the loop. The work don... In a circuit L, C and R are connected in series with an alternating voltage source of frquency$$f.$$The current leads the voltage by 45o. The value ... A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. Th... The magnetic flux through a circuit of resistance R changes by an amount$$\Delta \phi $$in a time$$\Delta $$t. Then the total quantity of elect... For a series LCR circuit the power loss at resonance is For a coil having L = 2 mH, current flow through it is$$I = {t^2}{e^{ - t}} then, the time at which emf become zero
A capacitor of capacity C has reactance X. If capacitance and frequency become double then reactance will be

## MCQ (More than One Correct Answer)

The value of quality factor is
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