2021
JEE Mains
MCQ
JEE Main 2021 (Online) 16th March Morning Shift
A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure
Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field $\overrightarrow B $ pointing into the page. An external agent pulls the bar to the left at a constant speed v.
The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is :
Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field $\overrightarrow B $ pointing into the page. An external agent pulls the bar to the left at a constant speed v.
The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is :
A.
Both I1 and I2 are in clockwise direction
B.
I1 is in clockwise direction and I2 is in anticlockwise direction
C.
I1 is in anticlockwise direction and I2 is in clockwise direction
D.
Both I1 and I2 are in anticlockwise direction
2021
JEE Mains
MCQ
JEE Main 2021 (Online) 26th February Evening Shift
An aeroplane, with its wings spread 10 m, is flying at a speed of 180 km/h in a horizontal direction. The total intensity of earth's field at that part is 2.5 $\times$ 10$-$4 Wb/m2 and the angle of dip is 60$^\circ$. The emf induced between the tips of the plane wings will be __________.
A.
88.37 mV
B.
62.50 mV
C.
54.125 mV
D.
108.25 mV
2021
JEE Mains
MCQ
JEE Main 2021 (Online) 24th February Evening Shift
Figure shows a circuit that contains four identical resistors with resistance R = 2.0$\Omega$, two identical inductors with inductance L = 2.0 mH and an ideal battery with emf E = 9V. The current 'i' just after the switch 'S' is closed will be :
A.
3.0 A
B.
3.37 A
C.
9 A
D.
2.25 A
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 5th September Evening Slot
An infinitely long, straight wire carrying current
I, one side opened rectangular loop and a
conductor C with a sliding connector are
located in the same plane, as shown, in the
figure. The connector has length $l$ and
resistance R. It slides to the right with a
velocity v. The resistance of the conductor and
the self inductance of the loop are negligible.
The induced current in the loop, as a function
of separation r, between the connector and the
straight wire is :
A.
${{{\mu _0}} \over {4\pi }}{{Ivl} \over {Rr}}$
B.
${{{\mu _0}} \over {\pi }}{{Ivl} \over {Rr}}$
C.
${{{\mu _0}} \over {2\pi }}{{Ivl} \over {Rr}}$
D.
${{2{\mu _0}} \over \pi }{{Ivl} \over {Rr}}$
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 4th September Morning Slot
A small bar magnet is moved through a coil at constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer G attached across the coil?
Three positions shown describe :
(a) the magnet's entry
(b) magnet is completely inside and
(c) magnet's exit.
Three positions shown describe :
(a) the magnet's entry
(b) magnet is completely inside and
(c) magnet's exit.
A.
B.
C.
D.
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 3rd September Evening Slot
A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of
a metal wire. The wire has a diameter of 4 mm and a total length of 30 cm. The magnetic field
changes with time at a steady rate ${{dB} \over {dt}}$ = 0.032 Ts–1. The induced current in the loop is close to
(Resistivity of the metal wire is 1.23 $ \times $ 10–8 $\Omega $m)
A.
0.53 A
B.
0.43 A
C.
0.34 A
D.
0.61 A
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 3rd September Morning Slot
An elliptical loop having resistance R, of semi major axis a, and semi minor axis b is placed in
magnetic field as shown in the figure. If the loop is rotated about the x-axis with angular frequency
$\omega $, the average power loss in the loop due to Joule heating is :
A.
${{\pi abB\omega } \over R}$
B.
${{{\pi ^2}{a^2}{b^2}{B^2}{\omega ^2}} \over R}$
C.
${{{\pi ^2}{a^2}{b^2}{B^2}{\omega ^2}} \over {2R}}$
D.
Zero
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 8th January Evening Slot
A shown in the figure, a battery of emf $\varepsilon $ is
connected to an inductor L and resistance R in
series. The switch is closed at t = 0. The total
charge that flows from the battery, between
t = 0 and t = tc (tc is the time constant of the
circuit) is :
A.
${{\varepsilon L} \over {e{R^2}}}$
B.
${{\varepsilon L} \over {{R^2}}}$
C.
${{\varepsilon L} \over {{R^2}}}\left( {1 - {1 \over e}} \right)$
D.
${{\varepsilon R} \over {e{L^2}}}$
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 8th January Morning Slot
At time t = 0 magnetic field of 1000 Gauss is
passing perpendicularly through the area
defined by the closed loop shown in the figure.
If the magnetic field reduces linearly to
500 Gauss, in the next 5s, then induced EMF
in the loop is :
A.
48 μV
B.
28 μV
C.
56 μV
D.
36 μV
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 7th January Evening Slot
A planar loop of wire rotates in a uniform magnetic field. Initially at t = 0, the plane of the loop
is perpendicular to the magnetic field. If it rotates with a period of 10 s about an axis in its plane
then the magnitude of induced emf will be maximum and minimum, respectively at :
A.
2.5 s and 7.5 s
B.
5.0 s and 10.0 s
C.
5.0 s and 7.5 s
D.
2.5 s and 5.0 s
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 7th January Morning Slot
Consider a circular coil of wire carrying constant current I, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by $\phi $i. The magnetic flux through the area of the circular coil area is given by $\phi $0. Which of the following option is correct?
A.
$\phi $i = $\phi $0
B.
$\phi $i < $\phi $0
C.
$\phi $i $>$ $\phi $0
D.
$\phi $i = - $\phi $0
2020
JEE Mains
MCQ
JEE Main 2020 (Online) 7th January Morning Slot
A long solenoid of radius R carries a time (t) - dependent current
I(t)=I0t(1 - t). A ring of radius 2R is placed coaxially near its middle. During the time interval 0 $ \le $ t $ \le $ 1, the induced current (IR) and the induced EMF(VR) in the ring change as :
I(t)=I0t(1 - t). A ring of radius 2R is placed coaxially near its middle. During the time interval 0 $ \le $ t $ \le $ 1, the induced current (IR) and the induced EMF(VR) in the ring change as :
A.
Direction of IR remains unchanged and VR is zero at t = 0.25
B.
Direction of IR remains unchanged and VR is maximum at t = 0.5
C.
At t = 0.25 direction of IR reverses and VR is maximum
D.
At t = 0.5 direction of IR reverses and VR is zero
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 12th April Morning Slot
The figure shows a square loop L of side 5 cm which is connected to a network of resistances. The whole setup is moving towards right with a constant speed of 1 cm s-1. At some instant, a part of L is in a uniform
magnetic field of 1 T, perpendicular to the plane of the loop. If the resistance of L is 1.7 $\Omega $, the current in the
loop at that instant will be close to :
A.
115 $\mu $A
B.
170 $\mu $A
C.
60 $\mu $A
D.
150 $\mu $A
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 9th April Evening Slot
Two coils 'P' and 'Q' are separated by some
distance. When a current of 3 A flows through
coil 'P', a magnetic flux of 10–3 Wb passes
through 'Q'. No current is passed through 'Q'.
When no current passes through 'P' and a
current of 2 A passes through 'Q', the flux
through 'P' is :-
A.
3.67 × 10–4 Wb
B.
3.67 × 10–3 Wb
C.
6.67 × 10–4 Wb
D.
6.67 × 10–3 Wb
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 9th April Evening Slot
A very long solenoid of radius R is carrying
current I(t) = kte–at(k > 0), as a function of time
(t $ \ge $ 0). counter clockwise current is taken to be
positive. A circular conducting coil of radius
2R is placed in the equatorial plane of the
solenoid and concentric with the solenoid. The
current induced in the outer coil is correctly
depicted, as a function of time, by :-
A.
B.
C.
D.
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 9th April Morning Slot
The total number of turns and cross-section area
in a solenoid is fixed. However, its length L is varied
by adjusting the separation between windings. The
inductance of solenoid will be proportional to :
A.
1/L2
B.
1/L
C.
L
D.
L2
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 8th April Morning Slot
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 is equal to the
rate at which magnetic energy is stored in the
inductor is :
A.
${2 \over {\ln 2}}$
B.
${\ln 2}$
C.
$2{\ln 2}$
D.
${1 \over 2}{\ln 2}$
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 12th January Evening Slot
A 10 m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0 ms–1, at right angles to the horizontal component of the earth's magnetic field of 0.3 $ \times $ 10–4 Wb/m2. The value of the induced emf in wire is :
A.
0.3 $ \times $ 10–3 V
B.
2.5 $ \times $ 10–3 V
C.
1.5 $ \times $ 10–3 V
D.
1.1 $ \times $ 10–3 V
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 11th January Evening Slot
A copper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear
dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per
unit length of the frame the same, then the self inductance of the coil:
A.
decreases by a factor of $9\sqrt 3 $
B.
increases by a factor of 27
C.
decreases by a factor of 9
D.
increases by a factor of 3
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 11th January Morning Slot
There are two long co-axial solenoids of same length $l$. The inner and outer coils have radii r1 and r2 and number of turns per unit length n1 and n2, respectively. The ratio of mutual inductance to the self - inductance of the inner-coil is :
A.
${{{n_2}} \over {{n_1}}}.{{{r_2}^2} \over {{r_1}^2}}$
B.
${{{n_2}} \over {{n_1}}}$
C.
${{{n_1}} \over {{n_2}}}$
D.
${{{n_2}} \over {{n_1}}}.{{{r_1}} \over {{r_2}}}$
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 10th January Evening Slot
The self induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10 A to 25 A in 1s, the change in the energy of the inductance is -
A.
740 J
B.
637.5 J
C.
540 J
D.
437.5 J
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 10th January Morning Slot
A solid metal cube of edge length 2 cm is moving in a positive y-direction at a constant speed of 6 m/s. There is a uniform magnetic field of 0.1 T in the positive z-direction. The potential difference between the two faces of the cube perpendicular to the x-axis, is -
A.
2mV
B.
12 mV
C.
6 mV
D.
1 mV
2019
JEE Mains
MCQ
JEE Main 2019 (Online) 9th January Morning Slot
A conducting circular loop made of a thin wire, has area 3.5 $ \times $ 10$-$3 m2 and resistance 10 $\Omega $. It is placed perpendicular to a time dependent magnetic field B(t) = (0.4T)sin(50$\pi $t). The field is uniform in space. Then the net charge flowing through the loop during t = 0 s and t = 10 ms is close to :
A.
0.14 mC
B.
0.7 mC
C.
0.21 mC
D.
0.6 mC
2018
JEE Mains
MCQ
JEE Main 2018 (Online) 16th April Morning Slot
A coil of cross-sectional area A having n turns is placed in a uniform magnetic field B. When it is rotated with an angular velocity $\omega ,$ the maxium e.m.f. induced in the coil will be:
A.
3 nBA$\omega $
B.
${3 \over 2}$ nBA$\omega $
C.
nBA$\omega $
D.
${1 \over 2}$ nBA$\omega $
2018
JEE Mains
MCQ
JEE Main 2018 (Online) 15th April Evening Slot
A copper rod of mass m slides under gravity on two smooth parallel rails, with separation l and set at an angle of $\theta $ with the horizontal. At the bottom rails are joined by a resistance R. There is a uniform magnetic field B normal to the plane of the rails, as shown in the igure. The terminal speed of the copper rod is :
A.
${{mg\,R\,\tan \,\theta } \over {{B^2}\,{l^2}}}$
B.
${{mg\,R\,\cot \,\theta } \over {{B^2}\,{l^2}}}$
C.
${{mg\,R\,\sin \,\theta } \over {{B^2}\,{l^2}}}$
D.
${{mg\,R\,\cos \,\theta } \over {{B^2}\,{l^2}}}$
2018
JEE Mains
MCQ
JEE Main 2018 (Online) 15th April Evening Slot
At the center of a fixed large circular coil of radius R, a much smaller circular coil of radius r is placed. The two coils are concentric and are in the same plane. The larger coil carries a current I. The smaller coil is set to rotate with a constant angular velocity $\omega $ about an axis along their common diameter. Calculate the emf induced in their smaller coil after a time t of its start of rotation.
A.
${{{\mu _o}{\rm I}} \over {2\,R}}$ $\omega $ $\pi $ r2 sin$\omega $ t
B.
${{{\mu _o}{\rm I}} \over {4\,R}}$ $\omega $ $\pi $ r2 sin$\omega $ t
C.
${{{\mu _o}{\rm I}} \over {4\,R}}$ $\omega $ r2 sin$\omega $ t
D.
${{{\mu _o}{\rm I}} \over {2\,R}}$ $\omega $ r2 sin$\omega $ t
2017
JEE Mains
MCQ
JEE Main 2017 (Online) 9th April Morning Slot
A uniform magnetic field B of 0.3 T is along the positive Z-direction. A rectangular loop (abcd) of sides 10 cm × 5 cm carries a current I of 12 A. Out of the following different orientations which one
corresponds to stable equilibrium ?
A.
B.
C.
D.
2017
JEE Mains
MCQ
JEE Main 2017 (Online) 8th April Morning Slot
A small circular loop of wire of radius a is located at the centre of a much larger circular wire loop of radius b. The two loops are in the same plane. The outer loop of radius b carries an alternating current I = Io cos ($\omega $t). The emf induced in the smaller inner loop is nearly :
A.
${{\pi {\mu _o}{I_o}} \over 2}.{{{a^2}} \over b}\,\omega \sin \left( {\omega t} \right)$
B.
${{\pi {\mu _o}{I_o}} \over 2}.{{{a^2}} \over b}\,\omega \cos \left( {\omega t} \right)$
C.
$\pi {\mu _o}{I_o}\,{{{a^2}} \over b}\omega \sin \left( {\omega t} \right)$
D.
${{\pi {\mu _o}{I_o}\,{b^2}} \over a}\omega \cos \left( {\omega t} \right)$
2017
JEE Mains
MCQ
JEE Main 2017 (Offline)
In a coil of resistance 100 $\Omega $, a current is induced by changing
the magnetic flux through it as shown in the figure. The
magnitude of change in flux through the coil is:
A.
275 Wb
B.
200 Wb
C.
225 Wb
D.
250 Wb
2016
JEE Mains
MCQ
JEE Main 2016 (Online) 10th April Morning Slot
Consider a thin metallic sheet perpendicular to the plane of the paper
moving with speed ‘v’ in a uniform magnetic field B going into the plane of the paper (See figure). If charge densities $\sigma $1 and $\sigma $2 are induced on the left and right surfaces, respectively, of the sheet then (ignore fringe effects) :
A.
$\sigma $1 = $ \in $0 $\upsilon $ B, $\sigma $2 = $-$ $ \in $0 $\upsilon $ B
B.
$\sigma $1 = ${{{ \in _0}\upsilon \,B} \over 2},$ $\sigma $2 = ${{ - { \in _0}\,\upsilon B} \over 2}$
C.
$\sigma $1 = $\sigma $2 = ${ \in _0}\,\upsilon B$
D.
$\sigma $1 = ${{ - { \in _0}\upsilon B} \over 2},$ $\sigma $2 = ${{ { \in _0}\upsilon B} \over 2},$
2016
JEE Mains
MCQ
JEE Main 2016 (Online) 10th April Morning Slot
A conducting metal circular-wire-loop of radius r is placed perpendicular to a
magnetic field which varies with time as
B = B0e${^{{{ - t} \over r}}}$ , where B0 and $\tau $ are constants, at time t = 0. If the resistance of the loop is R then the heat generated in the loop after a long time (t $ \to $ $\infty $) is :
B = B0e${^{{{ - t} \over r}}}$ , where B0 and $\tau $ are constants, at time t = 0. If the resistance of the loop is R then the heat generated in the loop after a long time (t $ \to $ $\infty $) is :
A.
${{{\pi ^2}{r^4}B_0^4} \over {2\tau R}}$
B.
${{{\pi ^2}{r^4}B_0^2} \over {2\tau R}}$
C.
${{{\pi ^2}{r^4}B_0^2R} \over \tau }$
D.
${{{\pi ^2}{r^4}B_0^2} \over {\tau R}}$
2015
JEE Mains
MCQ
JEE Main 2015 (Offline)
Two coaxial solenoids of different radius carry current $I$ in the same direction. $\overrightarrow {{F_1}} $ be the magnetic force on the inner solenoid due to the outer one and $\overrightarrow {{F_2}} $ be the magnetic force on the outer solenoid due to the inner one. Then :
A.
$\overrightarrow {{F_1}} $ is radially in wards and $\overrightarrow {{F_2}} = 0$
B.
$\overrightarrow {{F_1}} $ is radially outwards and $\overrightarrow {{F_2}} = 0$
C.
$\overrightarrow {{F_1}} = \overrightarrow {{F_2}} = 0$
D.
$\overrightarrow {{F_1}} $ is radially inwards and $\overrightarrow {{F_2}} $ is radially outards
2013
JEE Mains
MCQ
JEE Main 2013 (Offline)
A circular loop of radius $0.3$ $cm$ lies center of the small loop is on the axis of the bigger loop. The distance between their centers is $15$ $cm.$ If a current of $2.0$ $A$ flows through the smaller loop, than the flux linked with bigger loop is
A.
$9.1 \times {10^{ - 11}}\,$ weber
B.
$6 \times {10^{ - 11}}\,$ weber
C.
$3.3 \times {10^{ - 11}}\,$ weber
D.
$6.6 \times {10^{ - 9}}\,$ weber
2013
JEE Mains
MCQ
JEE Main 2013 (Offline)
A metallic rod of length $'\ell '$ is tied to a string of length $2$$\ell $ and made to rotate with angular speed $w$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field $'B'$ in the region, the $e.m.f$ induced across the ends of the rod is
A.
${{2B\omega \ell } \over 2}$
B.
${{3B\omega \ell } \over 2}$
C.
${{4B\omega {\ell ^2}} \over 2}$
D.
${{5B\omega {\ell ^2}} \over 2}$
2012
JEE Mains
MCQ
AIEEE 2012
A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to :
A.
development of air current when the plate is placed
B.
induction of electrical charge on the plate
C.
shielding of magnetic lines of force as aluminium is a para-magnetic material.
D.
electromagnetic induction in the aluminium plate giving rise to electromagnetic damping.
2011
JEE Mains
MCQ
AIEEE 2011
A boat is moving due east in a region where the earth's magnetic fields is $5.0 \times {10^{ - 5}}$ $N{A^{ - 1}}\,{m^{ - 1}}$ due north and horizontal. The best carries a vertical aerial $2$ $m$ long. If the speed of the boat is $1.50\,m{s^{ - 1}},$ the magnitude of the induced $emf$ in the wire of aerial is :
A.
$0.75$ $mV$
B.
$0.50$ $mV$
C.
$0.15$ $mV$
D.
$1$ $mV$
2010
JEE Mains
MCQ
AIEEE 2010
A rectangular loop has a sliding connector $PQ$ of length $l$ and resistance $R$ $\Omega $ and it is moving with a speed $v$ as shown. The set-up is placed in a uniform magnetic field going into the plane of the paper. The three currents ${I_1},{I_2}$ and $I$ are
A.
${I_1} = - {I_2} = {{Blv} \over {6R}},\,\,I = {{2Blv} \over {6R}}$
B.
${I_1} = {I_2} = {{Blv} \over {3R}},\,\,I = {{2Blv} \over {3R}}$
C.
${I_1} = {I_2} = I = {{Blv} \over R}$
D.
${I_1} = {I_2} = {{Blv} \over {6R}},I = {{Blv} \over {3R}}$
2008
JEE Mains
MCQ
AIEEE 2008
Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area $A=$ $10\,\,c{m^2}$ and length $=20$ $cm$ . If one of the solenoid has $300$ turns and the other $400$ turns, their mutual inductance is
$\left( {{\mu _0} = 4\pi \times {{10}^{ - 7}}\,Tm\,{A^{ - 1}}} \right)$
$\left( {{\mu _0} = 4\pi \times {{10}^{ - 7}}\,Tm\,{A^{ - 1}}} \right)$
A.
$2.4\pi \times {10^{ - 5}}H$
B.
$4.8\pi \times {10^{ - 4}}H$
C.
$4.8\pi \times {10^{ - 5}}H$
D.
$2.4\pi \times {10^{ - 4}}H$
2007
JEE Mains
MCQ
AIEEE 2007
An ideal coil of $10H$ is connected in series with a resistance of $5\Omega $ and a battery of $5V$. $2$ second after the connection is made, the current flowing in ampere in the circuit is
A.
$\left( {1 - {e^{ - 1}}} \right)$
B.
$\left( {1 - e} \right)$
C.
$e$
D.
${{e^{ - 1}}}$
2006
JEE Mains
MCQ
AIEEE 2006
Which of the following units denotes the dimension ${{M{L^2}} \over {{Q^2}}}$, where $Q$ denotes the electric charge?
A.
$Wb/{m^2}$
B.
Henry $(H)$
C.
$H/{m^2}$
D.
Weber $(Wb)$
2006
JEE Mains
MCQ
AIEEE 2006
An inductor $(L=100$ $mH)$, a resistor $\left( {R = 100\,\Omega } \right)$ and a battery $\left( {E = 100V} \right)$ are initially connected in series as shown in the figure. After a long time the battery is disconnected after short circuiting the points $A$ and $B$. The current in the circuit $1$ $ms$ after the short circuit is
A.
$1/eA$
B.
$eA$
C.
$0.1$ $A$
D.
$1$ $A$
2006
JEE Mains
MCQ
AIEEE 2006
The flux linked with a coil at any instant $'t'$ is given by
$\phi = 10{t^2} - 50t + 250$
The induced $emf$ at $t=3s$ is
$\phi = 10{t^2} - 50t + 250$
The induced $emf$ at $t=3s$ is
A.
$-190$ $V$
B.
$-10$ $V$
C.
$10$ $V$
D.
$190$ $V$
2005
JEE Mains
MCQ
AIEEE 2005
One conducting $U$ tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field $B$ is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed $v,$ then the $emf$ induced in the circuit in terms of $B,l$ and $v$ where $l$ is the width of each tube, will be
A.
$-Blv$
B.
$blv$
C.
$2$ $Blv$
D.
zero
2005
JEE Mains
MCQ
AIEEE 2005
A coil of inductance $300$ $mH$ and resistance $2\,\Omega $ is connected to a source of voltage $2$ $V$. The current reaches half of its steady state value in
A.
$0.1$ $s$
B.
$0.05$ $s$
C.
$0.3$ $s$
D.
$0.15$ $s$
2004
JEE Mains
MCQ
AIEEE 2004
In a uniform magnetic field of induction $B$ a wire in the form of a semicircle of radius $r$ rotates about the diameter of the circle with an angular frequency $\omega .$ The axis of rotation is perpendicular to the field. If the total resistance of the circuit is $R,$ the mean power generated per period of rotation is
A.
${{{{\left( {B\pi r\omega } \right)}^2}} \over {2R}}$
B.
${{{{\left( {B\pi {r^2}\omega } \right)}^2}} \over {8R}}$
C.
${{B\pi {r^2}\omega } \over {2R}}$
D.
${{{{\left( {B\pi r{\omega ^2}} \right)}^2}} \over {8R}}$
2004
JEE Mains
MCQ
AIEEE 2004
A coil having $n$ turns and resistance $R\Omega $ is connected with a galvanometer of resistance $4R\Omega .$ This combination is moved in time $t$ seconds from a magnetic field ${W_1}$ weber to ${W_2}$ weber. The induced current in the circuit is
A.
${{\left( {{W_2} - {W_1}} \right)} \over {Rnt}}$
B.
$ - {{n\left( {{W_2} - {W_1}} \right)} \over {5\,\,Rt}}$
C.
$ - {{\left( {{W_2} - {W_1}} \right)} \over {5\,\,Rnt}}$
D.
$ - {{n\left( {{W_2} - {W_1}} \right)} \over {Rt}}$
2004
JEE Mains
MCQ
AIEEE 2004
A metal conductor of length $1$ $m$ rotates vertically about one of its ends at angular velocity $5$ radians per second. If the horizontal component of earth's magnetic field is $0.2 \times {10^{ - 4}}T,$ then the $e.m.f.$ developed between the two ends of the conductor is
A.
$5mV$
B.
$50\mu V$
C.
$5\mu V$
D.
$50mV$
2003
JEE Mains
MCQ
AIEEE 2003
When the current changes from $ + 2A$ to $-2A$ in $0.05$ second, an $e.m.f.$ of $8$ $V$ is inducted in a coil. The coefficient of self- induction of the coil is
A.
$0.2H$
B.
$0.4H$
C.
$0.8$ $H$
D.
$0.1$ $H$
2003
JEE Mains
MCQ
AIEEE 2003
Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon
A.
the rates at which currents are changing in the two coils
B.
relative position and orientation of the two coils
C.
the currents in the two coils
D.
the materials of the wires of the coils
2002
JEE Mains
MCQ
AIEEE 2002
A conducting square loop of side $L$ and resistance $R$ moves in its plane with a uniform velocity $v$ perpendicular to one of its sides. A magnetic induction $B$ constant in time and space, pointing perpendicular and into the plane at the loop exists everywhere with half the loop outside the field, as shown in figure. The induced $emf$ is
A.
zero
B.
$RvB$
C.
$vBL/R$
D.
$vBL$
