Question 1 :
Alternating current is flowing in inductance L and resistance R. The frequency of source is $\displaystyle\frac{\omega}{2\pi}$. Which of the following statement is correct.
Question 2 :
Which of the following does not have the same dimensions as the Henry?
Question 3 :
Two concentric co-planar circular loops of radii $r_1$ and $r_2$ carry currents of respectively $i_1$ and $i_2$ in opposite directions (one clockwise and the other anticlockwise.) The magnetic induction at the centre of loops is half that due to $i_1$ alone at the centre. If $r_2 = 2r_1$. the value of $i_2 / i_1$ is
Question 5 :
If circular coil with $N_{1}$ turns is changed in to a coil of $N_{2}$ turns. What will be the ratio of self inductances in both cases.
Question 6 :
Henry, the SI unit of inductance can be written as :
Question 7 :
Multiple Correct Answers Type<br>The SI unit of inductance, henry, can be written as
Question 9 :
When the number of turns in a solenoid is doubled without any change in the length of the solenoid, its self-inductance becomes :
Question 10 :
A student measures the terminal potential difference (V) of a cell (of emf $\varepsilon$ and internal) resistance r) as a function of the current (I) flowing through it. The slope and intercept of the graph between V and I, then respectively equal to :<br><br><br><br>
Question 12 :
Two coils A and B have 200 and 400 turns respectively. A current of 1 A in coil A causes a flux per turn of $10^{-3}$ Wb to link with A and a flux per turn of $0.8 \times 10^{-3}$ Wb through B. The ratio of self-inductance of A and the mutual inductance of A and B is :
Question 13 :
In a transformer, coefficient of mutual inductance between primary and secondary coil is 0.2 H. When current changes by 5 Na in the primary, then: the induced era in the secondary will be
Question 14 :
Two coils $X$ and $Y$ are placed in a circuit such that a current changes by $3\ A$ in coil $X$ and magnetic flux changes of $1.2\ Wb$ occurs in $Y$. The value of mutual inductance of the coils is :<br/>
Question 15 :
In mutual induction<br>A: when current in one coil increases, induced current in neighbouring coil flows in the opposite direction<br>B: When current in one coil decreases, induced current in neighbouring coil flows in the opposite direction
Question 16 :
In case of all flux from the current in coil 1 links with coil2, the coefficient of coupling will be
Question 17 :
An inductor of inductance $100\ mH$ is connected in series with a resistance, a variable capacitance and an AC source of frequency $2.0\ kHz$; The value of the capacitance so that maximum current may be drawn into the circuit.
Question 18 :
If ‘N’is the number of turns in a coil, the value of self inductance varies as <br/>
Question 19 :
The average self-induced emf in a $25 m H$ solenoid when the current in it falls from $0.2 A$ to $0 A$ in $0.01$ second, is <br/>
Question 20 :
The coefficient of self inductance and the coefficient of mutual inductance have <br/>
Question 21 :
A varying current in a coil change from $10A$ to $0$ in $0.5$sec. If the average emf induced in the coil is $220V$, the self inductance of the coil is :<br/>
Question 24 :
In one second, a current of 10 A changes through a coil. The induced emf is 10V, then, self-inductance of the coil is
Question 25 :
The self-inductance of a long solenoid carrying current is independent of:
Question 26 :
When current flowing in a coil changes from $3A$ to $2A$ is one millisecond, $5\ volt$ emf is induced in it. The self-inductance of the coil will be
Question 27 :
A circular coil has $500$ turns of wire and its radius is $5cm$. The self inductance of the coil is:-
Question 28 :
When the number of turns in a coll is doubled without any change in the length of the coll, its self-inductance becomes
Question 29 :
A coil has self inductance of $0.01H$. The current through it is allowed to change at the rate of $1A$ in $10^{-2}$s. The induced emf is<br/>
Question 30 : <p>An airplane in which the distance between the tips of the wings is<b> 50 meter</b> is flying horizontally with a speed of <b>360 km/hour</b> over a place where the vertical component of earths magnetic field is $2.0 \times {10^{ - 4}}Testa.$ The potential difference between the tips of the wings would be:-</p>
Question 31 :
Assertion(A): The possibility of an electric bulb fusing is higher at the time of switching on and off.<br/>Reason(R): Inductive effects produce a large current at the time of switch-on and switch-off. <br/>
Question 32 :
Two coils A and B have mutual inductance $2\times 10^{-2}$ henry. If the current in the primary is $i = 5\sin (10\pi t)$ then the maximum value of e.m.f. induced in coil B is:
Question 33 :
The horizontal component of the earth's magnetic field at a place is $3 \times 10 ^ { - 4 } T$and the dip is $\theta$ = $t a n ^ { - 1 }$ (4/3). A metal rod of length 0. 25 m placed in the north-south position is moved at a constant speed of 10 cm/s towards the east. The e.m.f induced in the rod will be:
Question 34 :
When we move a conductor of length l with speed V perpendicular to the magnetic field B the motional emf induced in the conductor will be
Question 35 :
Whenever, current is changed in a coil, an induced e.m.f. is produced in the same coil. This property of the coil is due to<br/>
Question 37 :
Two sources of equal emf are connected to an external resistance R. The internal resistances of two sources are $R_{ 1 }$ and $R_{ 2 }$($R_{ 2 }$>$R_{ 1 }$). If the potential difference across the source having internal resistance $R_{ 2 }$ is zero, then;
Question 38 :
Under what condition will the strength of current in a wire of resistance R be the same for connection is series and in parallel of n identical cells each of the internal resistance r? When
Question 41 :
Assertion(A): An inductor in a D.C. circuit opposes both a steady current and a changing current.Reason(R): Induced emf is generated only when the flux linked with the inductor remains unchanged.<br/>
Question 43 :
Foran inductorcoil $L = 0.04H$ then work done by source to establish a current of 5A in it is:-
Question 46 :
If $0.1J$ of energy is stored for the flow of current of $0.2A$ in an inductor, then its inductance value is:
Question 48 :
If coil is placed perpendicular to field lines then number of lines passing through coil are :
Question 52 :
Assertion: Lenz's law violates the principle of conservation of energy
Reason: Induced emf always opposes the change in magnetic flux responsible for its production.
Question 53 :
Assertion: Lenz's law violates the principle of conservation of energy.
Reason: Induced emf always opposes the change in magnetic flux responsible for its production.
Question 54 :
The current drawn by a $220V$ DC series motor of armature resistance $0.50$ and back emf $200V$ is <br/>
Question 55 :
If the load current and flux of a DC motor are held constant and voltage applied across its armature is increased by 5%, the speed of motor will<br/>
Question 56 :
A lossless coaxial cable has a capacitance of $7\times { 10 }^{ -11 }$ F and an inductance of $0.39\mu H$. Calculate characteristic impedance of the cable.<br/>
Question 57 :
To measure the field $B$ between the poles of an electromagnet, a small test loop of area $1$ <br> $cm^{2}$, resistance $10$ <br> $\Omega $ and $20$ turns is pulled out of it. A galvanometer shows that a total charge of $2 \mu C $ passed through the loop. The value of $B$ is<br/>
Question 58 :
For a coil having $L=2mH$, current flow through it is $I={t}^{2}e^{-t}$ then the time at which emf becomes zero:
Question 59 :
The peak value of an alternating emf E given by<br> $ E = E_0 \,cos\, \omega t $<br>is $ 10\,V $ and frequency is $ 50\,Hz $ . At time $ t = (1/600) \,s $ , the instantaneous value of emf is
Question 61 :
A horizontal straight conductor when placed along south-north direction falls under gravity; there is
Question 62 :
A coil has $100$ turns. When a current of $5A$ produces a magnetic flux of $1\mu Wb$, the coefficient of self induction is :<br/>
Question 63 :
A conducting rod of length $l$ is moving in a transverse magnetic field of strength $B$ with velocity $v$. The resistance of the rod is $R$. The current in the rod is
Question 65 :
One conducting U tube can slide inside another as shown in figure, maintaining electric 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
Question 66 :
The flux linked with a coil at any instant 't' is given by $\phi=10t^2-50t+250$. The induced emf at $t=3s$ is<br>
Question 67 :
Read the following statements and answer whether the given statement is true or false.<br/>The Lenz's law is consistent with the law of conservation of energy.<br/>
Question 68 :
The coil is wound on an iron core and looped back on itself so that core has two sets of closely wound coils carrying current in opposite directions. The self inductance is
Question 69 :
Stepping up of voltage by a factor of 100,reduce the current by a factor of
Question 70 :
The time constant of an inductance coil is $2\times 10^{-3}s$. When a $90\Omega$ resistance is joined in series, the same constant becomes $0.5\times 10^{-3}s$. The inductance and resistance of the coil are
Question 71 :
The emf of a genetator is 12 V and its internal resistance is $1 K \Omega$.Om measuring its emf with a voltmeter of $5 K \Omega$ the reading will be:-
Question 72 :
The distance between the ends of the wings of an airplane is $50 m$. It is flying in a horizontal plane at a speed of $360 Km/hour$. The vertical component of earth's magnetic field at that place is $2.0 \times 10^{-4} Wb/m^2$, then the potential difference induced between the ends of the wings will be
Question 73 :
What is the self inductance of a coil in which an induced emf of $2V$ is set up, when the current is changing at the rate of $4As^{-1}$
Question 74 :
When a coil of cross-sectional area A and number of turns N is rotated in a uniform magnetic field B with angular velocity $\omega$, then the maximum emf induced in the coil will be
Question 75 :
A metallic wire bent in form of a semi-circle of radius 0.1 m is moved in a direction parallel to its plane, but perpendicular to a magnetic field $B = 20$ mT with a velocity of 10  m/s. What is the induced e.m.f. in wire?
Question 76 :
A circular coil  of mean radius of 7 cm and having 4000 tums is rotated at the rate of 1800 revolutions per minute in the earth's magnetic field (B = 0.5 Gauss ) , The peak value of emf induced is
Question 77 :
Find out the e.m.f. produced when the current changes from 0 to 1 A in 10 second, given $L = 10 \,\mu H$
Question 78 :
An athlete with 3m long iron rod in hand runs towards east with a speed of 30 kmph. The horizontal component of earth's magnetic field is $4 \times 10^{-5} Wb/m^2$. If he runs with the rod in horizontal and vertical positions then the induced emf generated in the rod in two cases will be
Question 79 :
Assertion: Lenzs law violates the principle of conservation of energy.
Reason: Induced e.m.f., opposes always the change in magnetic flux responsible for its production.
Question 80 :
The value of self inductance of a coil is $5H$. The value of current changes from $1A$ to $2A$ in $5\ sec$., then value of magnitude of induced emf in it :-
Question 81 :
The coefficients of self induction of two coils are $L_1 = $ 8 mH and $L_2=$ 2 mH respectively. The current rises in the two coils at the same rate. The power given to the two coils at any instant is same. The ratio of currents flowing in the coils will be :<br/>
Question 82 :
A metal ring is held horizontally and bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet<br>
Question 84 :
The current in a choke changes from 0 to 10 A in 5 seconds. If the inductance of the choke is 2 H the induced emf is
Question 85 :
An aluminium ring B faces an electromagnet A. The current $i$ through A can be altered. Then choose the correct options :
Question 86 :
A short solenoid (length $l$ and radius $r$, with $n$ turns per unit length) lies well inside and on the axis of a very long, coaxial solenoid (length $L$, radius $R$ and $N$ turns per unit length, with $R > r$). Current $I$ flows in the short solenoid. Choose the correct statement.
Question 87 :
A rectangular coil of $300$ turns has an average area of $25\ cm \times  10\ cm$. The coil rotates with a speed of $50\ cps$ in uniform magnetic field of strength $4 \, \times \, 10^{-2} \, T$ about an axis perpendicular to the field. The peak value of the induced emf is (in volt):
Question 88 :
Magnetic flux during time interval $\tau$ varies through a stationary loop of resistance $R$, as $\phi_B = at (\tau - t)$. Find the amount of heat generated during that time. Neglect the inductance of the loop.
Question 89 :
If '$N$' is the number of turns in a circular coil then the value of self inductance varies as.<br>
Question 90 :
The self induced e.m.f.in a 0.1 H coil when the current in it is changing at the rate of 200 ampere/second is
Question 91 :
The current flowing in a copper voltameter is 3.2 A. The number ofcopper ions $(Cu^{2+})$ deposited at the cathode per minute is
Question 92 :
Two similar circular loops carry equal currents in the same direction. On moving the coils further apart, the electric current will
Question 93 :
The magnetic flux linked with a coil satisfies the relation $\phi = 4t^{2} + 6t + 9$ Wb, where t is the time in second. The emf induced in the coil at $t = 2s$ is
Question 94 :
A uniform magnetic field exists in a region given by $\vec { B } =3\hat { i } +4\hat { j } +5\hat { k } $. A rod of length $5m$ along y-axis moves with a constant speed of $1m$ ${s}^{-1}$ along x axis. Then the induced emf in the rod will be
Question 95 :
The magnetic flux linked with a coil is given by an equation $\phi$ (in webers) $= 8t^2 + 3t + 5.$ The induced e.m.f. in the coil at the fourth second will be
Question 96 :
A long solenoid with length $l$ and a radius $R$ consists of $N$ turns of wire,Neglecting the end effects, find the self-inductance.<br/>
Question 97 :
The current in a coil of $L=40 mH$ is to be increased uniformly from $1A$ to $11A$ in $4$ milliseconds. The induced e.m.f. will be<br/>
Question 98 :
The current in a coil decreases from $1 A$ to $0.2 A .$ In $10$ sec. Calculate the coefficient ofself-inductance. If induced emf is $0.4$ volt.
Question 99 :
A coil of wire of a certain radius has $600$ turns and a self inductance of $108$ mH. The self inductance of a $2^{nd}$ similar coil of $500$ turns willbe
Question 100 :
The coefficient of mutual induction between two coils is 4 H. If the current in the primary reduces from 5A to zero in 10$^{-3}$ second then the induced emf in the secondary coil will be
Question 101 :
A thin circular ring of area $A$ is held perpendicular to a uniform magnetic field of induction $B$. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of the circuit is $R$. When the ring suddenly squeezed to zero area, the charge flowing through the galvanometer is :<br/>
Question 102 :
The magnetic flux density $B$ is changing in magnitude at a constant rate $dB/dt$. A given mass $m$ of copper, drawn into a wire of radius $a$ and formed into a circular loop of radius $r$ is placed perpendicular to the field $B$. The induced current in the loop is $i$. The resistivity of copper is $\rho$ and density is $d$. The value of the induced current $i$ is
Question 103 :
<br>The magnitude of the induced electric field in the orbit at any instant of time during the time interval of themagnetic field change, is
Question 104 :
A flat coil, $C$ of $n$ turn, area $A$ and resistance $R$, is placed in a uniform magnetic field of magnitude $B$. The plane of the coil is initially perpendicular to $B$. The coil is rotated by an angle $\theta$ about a diameter and charge of amount $Q$ flows through it. If the coil rotates with a constant angular velocity $\omega$, the emf induced in it:
Question 105 :
The magnetic field in a region is given by B=$\dfrac{B_0}{L}$y(k) where L is a fixed length. A conducting rod of length L lies along the Y-axis between the origin and the point (0.L,0). If the rod moves with a velocity v=$v_0$i, find the emf induced between thee ends of the rod.
Question 106 :
A plane electromagnetic wave in a non magnetic dielectric medium is given by $\bar{E} = \bar{E_0} ( 4 \times 10^{-7}x - 50 t)$ with distance being in meter and time in seconds. The dielectric constant of the medium is:
Question 107 :
Self inductance $L$ of long solenoid is being proportional to the number of turns $N$ as-<br>
Question 108 :
A generator with a circular coil of $100$ turns of area $2\times { 10 }^{ -2 }{ m }^{ 2 }$ is immersed in a $0.01T$ magnetic field and rotated at a frequency of $50Hz$. The maximum emf which is produced during a cycle is
Question 109 :
A hundred turns of insulated copper wire are wrapped around an iron cylinder of area $1 \times 10^{-3}m^2$ and are connected to a resistor. The total resistance in the circuit is 10 ohms. If the longitudinal magnetic induction in the iron changes from 1 weber $m^{-2}$, in the direction to 1 Weber $m^{-2}$ in the opposite direction, how much charge flows through the circuit
Question 111 :
A charge particle having mass m and charge $+q$, given a velocity $\vec { { V }_{ 0 } } =2\overset { - }{ i } +4\overset { - }{ j } m/s$ in a region where electric field and magnetic field exists. Magnetic field in the region is $\vec { B } =6\overset { - }{ i } -8\overset { - }{ j }$ (Tesla). It is observed of charged particle remains constant. Electric field in the region is:
Question 112 :
An $n$ sided regular polygon is inscribed in a circular region of radius $R$ using a wire of cross sectional radius $r$ and resistivity $\rho$. If the magnetic field in the circular region has a time rate of change given by $B$ then the current in the wire loop at any time is given by
Question 113 :
A short solenoid of length $4cm$, radius $2cm$ and $100$ turns is placed inside and on the axis of a long solenoid of length $80cm$ and $1500$ turns. A current of $3A$ flows through the short solenoid. The mutual inductance of two solenoids is
Question 114 :
A fan operates at 200 V(dc) consuming 1000 W when running at full speed. Its internal wiring has resistance $1 \omega $. When the fan runs at full speed, its speed becomes constant. This is because the torque due to the magnetic field inside the fan is balanced by the torque due to air resistance on the blades of the fan and torque due to friction between the fixed part and the shaft of the fan. The electrical power going into the fan is spent (i) in the internal resistance as heat, call it $P_1$(ii) in doing work against internal friction and air resistance producing heat, sound, etc. Call it $P_2$. When the coil of the fan rotates, an emf is also induced in the coil. This opposes the external emf applied to send the current into the fan. This emf is called back emf, call it e. Answer the following question when the fan is running at full speed.<br/><br/>The value of power $P_1$ is <br/>
Question 115 :
When the current in a coil changes from 8 ampere to 2 ampere in $3 \times 10^{-2}$ second, the e.m.f. induced in the coil is 2 volt. The self inductance of the coil (in millinery) is
Question 116 :
A circular coil of radius $10\ cm, 500$ turns and resistance $2\Omega$ is placed with its plane perpendicular to the horizontal component of the earth's magnetic field. If is rotated about its vertical diameter through $180^{\circ}m$ in $0.25\ s$. The current induced in the coil is<br>(Horizontal component of the earth's magnetic field at that place is $3.0\times 10^{-5}T)$.
Question 117 :
A coil of area $2{m}^{2}$ and resistance $4\Omega$ is placed perpendicular to a uniform magnetic field of $4T$. The loop is rotated by ${90}^{o}$ in $0.1$ second. Choose the correct options
Question 118 :
A coil of $n$ turns and radius $r$ is placed in a magnetic field. The electrical power is dissipated due to the current induced in the coil. By stretching the wire, if the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be :<br/>
Question 120 :
A coil of 100 turns and 5 square centimeter is placed in a magnetic field B = 0.2 T. The normal to the plane of the coil makes an angle of 60 with the direction of the magnetic field. The magnetic flux linked with the coil is :
Question 121 :
A flat circular coil of $n$ turns, area $A$ and resistance $R$ is placed in a uniform magnetic field $B$. The plane of coil is initially perpendicular to $B$. When the coil is rotated through an angle of ${180}^{o}$ about one of its diameter, a charge ${Q}_{1}$ flows through the coil. When the same coil after being brought to its initial position, is rotated through an angle of ${360}^{o}$ about the same axis a charge ${Q}_{2}$ flows through it. Then ${Q}_{2}/{Q}_{1}$
Question 123 :
A long solenoid of radius $R$ carries a time (t)-dependent current $I(t)=I_0t(1-t)$. A ring of radius $2R$ is placed coaxially near its middle. During the time interval $0\le t\le 1$, the induced current $(I_R)$ and the induced $EMF(V_R)$ in the ring change as:
Question 124 :
The magnetic flux $\phi$ linked with a  conducting coil depends on time as $\phi=4t^n +6$ where n is a positive constant. The induced emf in the coil is e.
Question 125 :
The magnitude of the earth's magnetic field at the north pole is ${B}_{0}$. A horizontal conductor of length $l$ moves with a velocity $v$. The direction of $v$ is perpendicular to the conductor. The induced emf is
Question 126 :
A solenoid has $2000$ turns wound over a length of $0.3 m$. Its cross-sectional area is equal to $1.2\times 10^{-3} m^2$. Around its central cross-section, a coil of 300 turns is wound. If an initial current of $2 A$ flowing in the solenoid is reversed in $ 0.25 s$, the emf induced in the coil is
Question 127 :
A vertical ring of radius $r$ and resistance $R$ falls vertically. It is in contact with two vertical rails which are joined at the top. The rails are without friction and resistance. There is a horizontal uniform magnetic field of magnitude $B$ perpendicular to the plane of the ring and the rails. When the speed of the ring is $v$, the current in the top horizontal of the rail section is
Question 128 :
The magnetic field in a region is given by B=$\dfrac{B_0}{L}$y(k) where L is a fixed length. A conducting rod of length L lies along the Y-axis between the origin and the point (0.L,0). If the rod moves with a velocity v=$v_0$i, find the emf induced between thee ends of the rod.
Question 129 :
A uniform magnetic field exists in region given by $\vec{B}=3\hat{i}+4\hat{j}+5\hat{k}$. A rod of length $5$m is placed along y-axis is moved along x-axis with constant speed $1$m$/$sec. Then induced e.m.f. in the rod will be.
Question 130 :
A circular coil of mean radius of $7$cm and having $4000$ turns is rotated at the rate of $1800$ revolutions per minute in the earth's magnetic field (B$=0.5$ gauss), the peak value of emf induced in coil will be?
Question 131 :
Assertion : Lenz's Law violates the principle ofconservation of energy<br>Reason : Induced emf always opposes thechange in magnetic flux responsible for itsproduction.<br>
Question 132 :
A circular loop of radius $r$, having $N$ turns of a wire, is placed in a uniform and constant magnetic field $B$. The normal loop makes an angle $\theta$ with the magnetic field. Its normal rotates with an angular velocity $\omega$ such that the angle $\theta$ is constant. Choose the correct statement from the following.
Question 133 :
A ring of resistance $10 \Omega $ , radius $10cm$ and $100$ turns is rotated $100$ revolutions per second about a fixed axis which is perpendicular to a uniform magnetic field of induction $ 10 m T $ . The amplitude of the current in the loop will be nearly (Take $ \pi^2 = 10 $)
Question 134 :
There is a uniform magnetic field B normal to the xy plane. A conductor ABC has length $AB=l_{1}$, parallel to the x-axis, the length $BC=l_{2}$, parallel to the y axis. ABC moves in the xy plane with velocity $ v_{x} \hat {i} + v_{y} \hat{j} $. The potential difference between A and C is proportional to :
Question 135 :
Assertion: Induced potential across a coil and therefore induced current is always opposite to the direction of current due to external source.
Reason: Lenz's law states that induced emf always opposes the cause due to which it is being produced.
Question 136 :
An air cored solenoid with length 20 cm, area of cross section is 20 $cm^2$ and the number of turns 400 carries a current 2 A. The current is suddenly switched off within $10^{-3}$ sec. The average back emf induced across the end of the open switch in the circuit is ( ignore variation in magnetic field near the end of the solenoid)
Question 137 :
A long solenoid having $200$ turns per cm carries a current of $1.5 amp.$ At the centre of it is placed a coil of $100$ turns of cross-sectional are $3.14\times 10^{-4}m^2$ having its axis parallel to the field produced by the solenoid. When the direction of current in the solenoid is reversed within $0.05 sec,$ the induced e.m.f. in the coil is<br/>
Question 138 :
Electric charge $q$ is distributed uniformly over a rod of length $l$. The rod is placed parallel to a long wire carrying a current $i$. The separation between the rod and the wire is $a$. The force needed to move the rod along its length with a uniform velocity $v$ is :<br/>
Question 139 :
A Rowland ring of mean radius $15cm$ has $3500$ turns of wire wound on a ferromagnetic core of relative permeability $800$. What is the magnetic field $B$ in the core for a magnetising current of $1.2A$ ?
Question 140 :
Two coils have a mutual inductance $0.005\ H$. The current changes in the first coil according to the equation $i = i_{m}\sin \omega t$ where $i_{m} = 10\ A$ and $\omega = 100\pi \ rad\ s^{-1}$. The maximum value of the emf induced in the second coil is
Question 141 :
Two identical coaxial circular loops carry a current I each<br/>circulating in the same direction If the loops approach each other, you will observe that<br/>
Question 143 :
Assertion: Induced potential across a coil and therefore induced current is always opposite to the direction of current due to external source.
Reason: Lenz's law states that induced emf always opposes the cause due to which it is being produced.
Question 144 :
A loop of area $4 \ m^{2}$ is placed flat in the x-y plane.There is a constant magnetic field $4 T\hat  { j }$ in the region. Find the flux through the loop<br/>
Question 145 :
Find the inductance of a solenoid of length $l_0$, made of Cu windings of mass $m$. The winding resistance is equal to $R$. The diameter of solenoid << $l$. $\rho_0$ is resistivity of Cu and $\rho$ is density of the Cu.
Question 147 :
Magnetic flux linked with a stationary loop resistance $R$ varies with respect to time during the time period $T$ as follows:<br>$\phi=at(T-t)$<br>The amount of heat generated in the loop during that time (inductance of the coil is negligible) is
Question 148 :
Light with energy flux of 18$\mathrm { w } / \mathrm { cm } ^ { 2 }$ falls on a non reflecting surface of area 20$\mathrm { cm } ^ { 2 }$ at normal incidence the momentum delivered in $30$ minutes ise
Question 149 :
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 flux $ W_{1}$ to $ W_{2}$. The induced current in the circuit is<br/>
