Physics - Electromagnetic Induction - Quiz-5

A cycle wheel of radius 0.5 m is rotated with a constant angular velocity of 10 rad/s in a region of a magnetic field of 0.1 T which is perpendicular to the plane of the wheel. The EMF generated between its centre and the rim is:

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0.25 V
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0.125 V
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0.5 V
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zero

A proton is moving with constant speed towards a conducting ring placed in the same plane along with the path OP. The direction of the path of proton ahead of 'P' is

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Along with A
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Along with B
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Along with C
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Along any path depending upon the speed of the proton

A coil has 500 turns and the flux through the coil is $ϕ$ = 3t²+4t+9 milliweber. The magnitude of induced emf between the ends of the coil at t = 5 s is:

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34 millivolt
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17 volt
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17 millivolt
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34 volt

A circular wheel of 24 spokes is rotated at 300 rpm in a uniform magnetic field of 2 $\times$ 10^-3 tesla. Length of each spoke is 25 cm and the magnetic field is along the axis of the wheel, then the value of induced emf between rim and center of the wheel is

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1.96mV
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19.6V
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47.1mV
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19.6mV

When the length of a solenoid and number of turns per unit length is doubled, then the self-inductance of solenoid becomes/remains

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4 times
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2 times
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Unchanged
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8 times

When the current through a solenoid increases at a constant rate, the induced current

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is constant and is in the direction of inducing current.
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is constant and is in the direction opposite to the inducing current.
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is increasing and is in the direction of inducing current.
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is increasing and is in the direction opposite to inducing current.

A non-conducting ring having a uniformly distributed negative charge is placed in the plane of smooth paper. A uniformly decreasing inward magnetic field is passing through the ring. Then,

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Ring will start rotating anticlockwise.
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Ring will start rotating clockwise.
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Ring will jump and becomes floating above the paper.
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No change will be observed in the position of the ring.

A motor having an armature resistance 2 $Ω$ is operating at 220 volts. At full speed, the back emf of the motor is 200 volts. Then the value of current in the armature at full speed is

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100 A
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10 A
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110 A
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0.55 A

The current I in an inductance coil varies with time t according to the graph shown in the figure. Which one of the following plots shows the variation of voltage in the coil with time?

A square loop enters into a uniform magnetic field. The sides of the square are 5 cm and its speed is 1 cm/s. Its front edge enters into the magnetic field at t=0, then which curve represents the variation of induced emf V?

The figure shows a current-carrying wire whose current is increasing continuously, then the direction of induced current in the conducting loop placed in the plane of paper is?

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Anticlockwise
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Clockwise
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Zero
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First clockwise then anticlockwise

Work done in increasing the current through a solenoid from 0 to 2 A is 20 J. Work done in increasing the current from 4 to 6 A is

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100 J
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60 J
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80 J
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120 J

A wire of length 6 m is rotated about the axis passing through point C and parallel to the magnetic field lines with angular velocity 4 radian/second. If B = 0.5T, the potential difference across the ends of the wire is

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2 V
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6 V
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12 V
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Zero

The current flowing in an inductor of inductance 2.0 H varies as i = 2 sin(40t + $π / 3$ ), where i is in amperes and t is in seconds. The maximum value of the emf induced in the inductor is:

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320 V
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160 V
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80 V
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4 V

If a magnet is allowed to fall through a long conducting pipe, then the final acceleration of the magnet will be

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= g
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$> g$
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Zero
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$\geq g$

In a uniform magnetic field, a ring is rotating about its axis which is parallel to the magnetic field and the magnetic field is perpendicular to the plane of the ring. The induced electric field in the ring:

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is zero.
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depends on the radius of the ring.
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depends on the nature of the material of the ring.
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depends on the product of the magnetic field and speed.

Which of the following is not based on the application of eddy currents?

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Speedometer
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Dead-beat galvanometer
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Energy meter
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Tangent galvanometer

A railway track running north-south has two parallel rails l distance apart. If H is the horizontal component of the earth's field, angle of dip is $θ$ , then the induced emf between the rails when a train passes with velocity v, is

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Hlvtan $θ$
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Hlv
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3. Hlvcos $θ$
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Hlvsin $θ$

Two coils of self-inductance L₁ and L₂ are placed so close together that they completely link the magnetic flux of each other. If M be their mutual inductance then, the correct relation is

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M = $\sqrt{\frac{L_{1}}{L_{2}}}$
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M = L₁ $\sqrt{L_{2}}$
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M = L₁L₂
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M = $\sqrt{L_{1} L_{2}}$

Calculate the self-inductance of a solenoid having 1000 turns and length 1m. The area of cross-section is 7 cm² and $μ_{r}$ = 1000.

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888 H
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0.88 H
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0.088 H
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88.8 H

What is the effective self-inductance of two solenoids in series-wound on a core as shown in the figure, if L is the self-inductance of each solenoid?

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L
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2L
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L/2
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Zero

A uniform conductor having length l is moving in uniform magnetic field B with speed v. If B, l and v are mutually perpendicular and R is the resistance of the conductor, then the power delivered by the external source is

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B²l²v²/2R
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2B²l²v²/R
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B²l²v²/R
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Zero

A circular ring of radius r is at the centre of a square having side a (a $≫$ r). The mutual inductance of the system is :

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$\frac{μ_{0} r^{2}}{a}$
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$\frac{\sqrt{2} μ_{0} r^{2}}{π}$
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$\frac{2 \sqrt{2} μ_{0} r^{2}}{a}$
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$\frac{2 \sqrt{2} μ_{0} r^{2}}{π a}$

If a semicircular conducting loop ACB is rotating in the plane of paper with constant angular velocity $ω$ about O, then which of the following graphs shows the variation of induced current (l) with time (t)? The magnetic field is perpendicular to the plane of the loop as shown in the figure.

A current-carrying cable is penetrating a loop as shown in the figure. If the magnitude of the current is decreasing with time, then the current induced in the loop is

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Zero
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Clockwise
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Anticlockwise
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Depends on the magnitude of the current

A solenoid has an inductance of 20 H and a resistance of 5 ohms. It is connected to a battery of 20 volts. The maximum magnetic energy stored in the magnetic field of the solenoid is

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40 J
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160 J
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320 J
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80 J

The slotting processes in a metallic sheet causes-

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the increase of the resistance in the path for circulation of current.
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decrease in the strength of eddy current.
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feeble the electromagnetic damping.
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All of these

The square loop shown below is rotated about the axis PQ and magnetic field is perpendicular to the plane of the paper. The magnitude of induced emf in the loop is minimum when the plane of the loop:

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is perpendicular to the plane of the paper.
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is parallel to the plane of the paper.
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makes 45 $°$ angle with the plane of the paper.
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makes 60 $°$ angle with the plane of the paper.

A small square-shaped loop of edge length l is placed at the centre of a circular loop A of radius r with its plane perpendicular to the plane of the circular loop. The coefficient of mutual induction of this combination is

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Zero
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$\frac{μ_{0} \sqrt{2} l r^{2}}{3 π}$
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$\frac{μ_{0} \sqrt{2} l^{2} r}{3}$
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$\frac{μ_{0} \sqrt{3} l^{2}}{2 r}$

A horizontal ring of radius r spins about its vertical axis with an angular velocity $ω$ in a uniform vertical magnetic field of magnitude B. The emf induced in the ring is

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Zero
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$π r^{2} B ω$
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$\frac{1}{2} B ω r^{2}$
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$B ω r^{2}$

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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