The adjoining figure shows two bulbs B 1 and B 2 resistor R and an inductor L . When the switch S is turned off

Both B 1 and B 2 die out with some delay

Both B 1 and B 2 die out promptly

B 1 dies out promptly but B 2 with some delay

B 2 dies out promptly but B 1 with some delay

Physics - Electromagnetic Induction - Quiz-2

If a current of 10 A flows in one second through a coil, and the induced e.m.f. is 10 V, then the self-inductance of the coil is

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$\frac{2}{5} H$
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$\frac{4}{5} H$
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$\frac{5}{4} H$
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1 H

The adjoining figure shows two bulbs B₁ and B₂ resistor R and an inductor L. When the switch S is turned off

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Both B₁ and B₂ die out promptly
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Both B₁ and B₂ die out with some delay
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B₁ dies out promptly but B₂ with some delay
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B₂ dies out promptly but B₁ with some delay

An inductance L and a resistance R are first connected to a battery. After some time the battery is disconnected but L and R remain connected in a closed circuit. Then the current reduces to 37% of its initial value in time ?

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RL sec
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$\frac{R}{L} s e c$
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$\frac{L}{R} s e c$
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$\frac{1}{L R} s e c$

In an LR-circuit, the time constant is that time in which current grows from zero to the value (where I₀ is the steady-state current)

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0.63 I₀
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0.50 I₀
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0.37 I₀
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I₀

In the figure magnetic energy stored in the coil is

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Zero
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Infinite
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25 joules
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None of the above

A copper rod of length l is rotated about one end perpendicular to the magnetic field B with constant angular velocity ω. The induced e.m.f. between the two ends is

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$\frac{1}{2} B ω l^{2}$
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$\frac{3}{4} B ω l^{2}$
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$B ω l^{2}$
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$2 B ω l^{2}$

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

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R₁/R₂
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R₂/R₁
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$R_{1}^{2} / R_{2}$
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$R_{2}^{2} / R_{1}$

A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is

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Zero
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$B ν π R^{2} / 2$ and M is at the higher potential
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2RBV and M is at the higher potential
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2RBV and Q is at the higher potential

Consider the situation shown in the figure. The wire AB is sliding on the fixed rails with a constant velocity. If the wire AB is replaced by semicircular wire, the magnitude of the induced current will

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Increase
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Remain the same
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Decrease
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Increase or decrease depending on whether the semicircle bulges towards the resistance or away from it

A circular loop of radius R carrying current I lies in the x-y plane with its centre at the origin. The total magnetic flux through the x-y plane is

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Directly proportional to I
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Directly proportional to R
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Directly proportional to R²
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Zero

A small square loop of wire of side l is placed inside a large square loop of wire of side L (L > l). The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to

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l / L
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l² / L
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L/l
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L²/l

A uniform but time-varying magnetic field B(t) exists in a circular region of radius a and is directed into the plane of the paper, as shown. The magnitude of the induced electric field at point P at a distance r from the centre of the circular region

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Is zero
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Decreases as $\frac{1}{r}$
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Increases as r
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Decreases as $\frac{1}{r^{2}}$

A coil of wire having finite inductance and resistance has a conducting ring placed coaxially within it. The coil is connected to a battery at time t = 0 so that a time-dependent current I₁(t) starts flowing through the coil. If I₂(t) is the current induced in the ring and B(t) is the magnetic field at the axis of the coil due to I₁(t), then as a function of time (t > 0), the product I₂ (t) B(t)

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Increases with time
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Decreases with time
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Does not vary with time
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Passes through a maximum

Two circular coils can be arranged in any of the three situations shown in the figure. Their mutual inductance will be

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Maximum in situation (A)
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Maximum in situation (B)
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Maximum in situation (C)
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The same in all situations

A conducting rod of length 2l is rotating with constant angular speed $ω$ about its perpendicular bisector. A uniform magnetic field $\vec{B}$ exists parallel to the axis of rotation. The e.m.f. induced between two ends of the rod is

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BΩl²
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$\frac{1}{2} B ω l^{2}$
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$\frac{1}{8} B ω l^{2}$
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Zero

As shown in the figure, P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current I_P flows in P (as seen by E) and an induced current $I_{Q_{1}}$ flows in Q. The switch remains closed for a long time. When S is opened, a current $I_{Q_{2}}$ flows in Q. Then the directions of $I_{Q_{1}}$ and $I_{Q_{2}}$ (as seen by E) are

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Respectively clockwise and anticlockwise
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Both clockwise
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Both anticlockwise
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Respectively anticlockwise and clockwise

A conducting wireframe is placed in a magnetic field that is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced current in wires AB and CD are

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B to A and D to C
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A to B and C to D
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A to B and D to C
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B to A and C to D

A square metallic wire loop of side 0.1 m and resistance of 1Ω is moved with a constant velocity in a magnetic field of 2 wb/m² as shown in figure. The magnetic field is perpendicular to the plane of the loop, loop is connected to a network of resistances. What should be the velocity of loop so as to have a steady current of 1mA in loop?

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1 cm/sec
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2 cm/sec
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3 cm/sec
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4 cm/sec

A conductor ABOCD moves along its bisector with a velocity of 1 m/s through a perpendicular magnetic field of 1 wb/m², as shown in fig. If all the four sides are of 1m length each, then the induced emf between points A and D is

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0
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1.41 volt
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0.71 volt
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None of the above

A conducting rod PQ of length L = 1.0 m is moving with a uniform speed v = 2 m/s in a uniform magnetic field B = 4.0 T directed into the paper. A capacitor of capacity C = 10 μF is connected as shown in figure. Then

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q_A = + 80 μC and q_B = – 80 μC
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q_A = – 80 μC and q_B = + 80 μC
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q_A = 0 = q_B
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Charge stored in the capacitor increases exponentially with time

The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is 10Ω. The current in the circuit will be now

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i = 0.5 A
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i > 0.5 A
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i < 0.5 A
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i = 0

Shown in the figure is a circular loop of radius r and resistance R. A variable magnetic field of induction B = B₀e^–t is established inside the coil. If the key (K) is closed, the electrical power developed right after closing the switch, at t=0, is equal to

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$\frac{B_{0}^{2} π r^{2}}{R}$
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$\frac{B_{0} 10 r^{3}}{R}$
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$\frac{B_{0}^{2} π^{2} r^{4} R}{5}$
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$\frac{B_{0}^{2} π^{2} r^{4}}{R}$

A highly conducting ring of radius R is perpendicular to and concentric with the axis of a long solenoid as shown in fig. The ring has a narrow gap of width d in its circumference. The solenoid has a cross-sectional area A and a uniform internal field of magnitude B₀. Now beginning at t = 0, the solenoid current is steadily increased so that the field magnitude at any time t is given by B(t) = B₀ + αt where α > 0. Assuming that no charge can flow across the gap, the end of the ring which has an excess of positive charge and the magnitude of induced e.m.f. in the ring are respectively

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X, Aα
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X πR²α
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Y, πA²α
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Y, πR²α

A rectangular loop with a sliding connector of length l = 1.0 m is situated in a uniform magnetic field B = 2T perpendicular to the plane of the loop. Resistance of connector is r = 2Ω. Two resistance of 6Ω and 3Ω are connected as shown in the figure. The external force required to keep the connector moving with a constant velocity v = 2m/s is

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6 N
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4 N
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2 N
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1 N

A wire cd of length l and mass m is sliding without friction on conducting rails ax and by as shown. The vertical rails are connected to each other with a resistance R between a and b. A uniform magnetic field B is applied perpendicular to the plane abcd such that cd moves with a constant velocity of

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$\frac{m g R}{B l}$
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$\frac{m g R}{B^{2} l^{2}}$
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$\frac{m g R}{B^{3} l^{3}}$
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$\frac{m g R}{B^{2} l}$

A conducting rod AC of length 4l is rotated about a point O in a uniform magnetic field $\vec{B}$ directed into the paper. AO = l and OC = 3l. Then

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$V_{A} - V_{O} = \frac{B ω l^{2}}{2}$
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$V_{O} - V_{C} = \frac{7}{2} B ω l^{2}$
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$V_{A} - V_{C} = 4 B ω l^{2}$
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$V_{C} - V_{O} = \frac{9}{2} B ω l^{2}$

The figure shows three circuits with identical batteries, inductors, and resistors. Rank the circuits according to the current through the battery (i) just after the switch is closed and (ii) a long time later, greatest first:

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(i) i₂ > i₃ > i₁ (i₁ = 0) (ii) i₂ > i₃ > i₁
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(i) $i_{2} < i_{3} < i_{1} (i_{1} \neq 0)$ (ii) i₂ > i₃ > i₁
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(i) i₂ = i₃ = i₁ (i₁ = 0) (ii) i₂ < i₃ < i₁
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(i) $i_{2} = i_{3} > i_{1} (i_{1} \neq 0)$ (ii) i₂ > i₃ > i₁

The network shown in the figure is a part of a complete circuit. If at a certain instant the current i is 5 A and is decreasing at the rate of 10³ A/s then V_B – V_A is

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5 V
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10 V
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15 V
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20 V

A simple pendulum with bob of mass m and conducting wire of length L swings under gravity through an angle 2θ. The earth’s magnetic field component in the direction perpendicular to swing is B. Maximum potential difference induced across the pendulum is

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$2 B L \sin (\frac{θ}{2}) {(g L)}^{1 / 2}$
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$B L \sin (\frac{θ}{2}) {(g L)}^{\frac{1}{2}}$
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$B L \sin (\frac{θ}{2}) {(g L)}^{3 / 2}$
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$B L \sin (\frac{θ}{2}) {(g L)}^{2}$

The variation of induced emf (E) with time (t) in a coil if a short bar magnet is moved along its axis with a constant velocity is best represented as

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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