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Practice QuestionsMCQ (Single Correct Answer)
1
$A B$ is a part of an electrical circuit (see figure). The potential difference " $V_A-V_B$ ", at the instant when current $i=2 \mathrm{~A}$ and is increasing at a rate of $1 \mathrm{amp} /$ second is:
NEET 2025
2
Let us consider two solenoids $$A$$ and $$B$$, made from same magnetic material of relative permeability $$\mu_r$$ and equal area of cross-section. Length of $$A$$ is twice that of $$B$$ and the number of turns per unit length in $$A$$ is half that of $$B$$. The ratio of self inductances of the two solenoids, $$L_A: L_B$$ is
NEET 2024 (Re-Examination)
3
An emf is generated by an ac generator having 100 turn coil, of loop area $$1 \mathrm{~m}^2$$. The coil rotates at a speed of one revolution per second and placed in a uniform magnetic field of $$0.05 \mathrm{~T}$$ perpendicular to the axis of rotation of the coil. The maximum value of emf is :-
NEET 2023 Manipur
4
The net magnetic flux through any closed surface is :
NEET 2023
5
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 is
NEET 2022 Phase 2
6
A square loop of side 1 m and resistance 1 $$\Omega$$ is placed in a magnetic field of 0.5 T. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is
NEET 2022 Phase 1
7
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 M between them will be directly proportional to :
NEET 2021
8
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 any of its coplanar axis in 0.1 s, the emf induced in the coil will be :
NEET 2019
9
In which of the following devices, the eddy current effect is not used?
NEET 2019
10
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 placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10 $$\pi $$2 $$\Omega $$, the total charge flowing through the coil during this time is
NEET 2017
11
A uniform magnetic field is restricted within a region of rafius r. The magnetic field changes with time at a rate $${{d\overrightarrow B } \over {dt}}$$. Loop 1 of radius R > r encloses the region r and loop 2 of radius R is outside the region of magnetic field as shown in the figure. Then the e.m.f. generated is
NEET 2016 Phase 2
12
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 $$ \times \,{10^{ - 3}}$$ Wb. The self-inductance of the solenoid is
NEET 2016 Phase 1
13
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 any, induced in the coil ?
AIPMT 2015
14
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.
The potential difference developed across the ring when its speed is $$v$$, is
The potential difference developed across the ring when its speed is $$v$$, is
AIPMT 2014
15
A current of 2.5 A flows through a coil of inductance 5 H. The magnetic flux linked with the coil is
NEET 2013 (Karnataka)
16
A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is
NEET 2013
17
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. The magnitude of change in flux through the coil in weber is
AIPMT 2012 Mains
18
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) as $$\phi = 50{t^2} + 4$$.
The current in the coil at t = 2 sec is
The current in the coil at t = 2 sec is
AIPMT 2012 Prelims
19
The current $$i$$ in a coil varies with time as shown in the figure. The variation of induced emf with time would be
AIPMT 2011 Prelims
20
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 to shrink at a constant rate of 1 mm s$$-$$1. The induced emf when the radius is 2 cm, is
AIPMT 2010 Prelims
21
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 velocity. $$\overrightarrow V = v\widehat i$$. The magnetic field is directed along the negative z axis direction. The induced emf, during the passes of these loops, out of the field region, will not remain constant for
AIPMT 2009
22
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 starts shrinking at 2 mm/s. The induced emf in the loop when the radius is 2 cm is
AIPMT 2009
23
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 $$ \times $$ 10$$-$$3 Wb. The self-inductance of the solenoid is
AIPMT 2008
24
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 a way that its axis makes an angle of 60o with $$\overrightarrow B .$$ The magnetic flux linked with the disc is
AIPMT 2008
25
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 mutual inductance between these coils is
AIPMT 2006
26
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 done (joule) in taking a charge Q coulomb once along the loop is
AIPMT 2005
27
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 electric charge Q that passes any point in the circuit during the time $$\Delta $$t is represented by
AIPMT 2004
28
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
AIPMT 2001