JEE Main & Advanced Physics Electro Magnetic Induction Question Bank

done Mock Test - Electromagnetic Induction Total Questions - 25

• question_answer1)
  A thin semicircular conducting ring of radius R is fallin 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
  A)
  Zero done clear
  B)
  \[Bv\pi {{R}^{2}}/2\] and M is at higher potential done clear
  C)
  \[\pi RBv\]and Q is at higher potential done clear
  D)
  \[2RBv\]and Q is at higher potential done clear
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• question_answer2)
  Plane figures made of thin wires of resistance R = 50 milli ohm/metre are located in a uniform magnetic field  perpendicular into the plane  of the figures and which decrease at the rate dB/dt= 0.1 mT/s. Then currents in the inner and outer boundary are. (The inner radius a = 10 cm and outer radius b = 20 cm)
  A)
  \[{{10}^{-4}}A\](Clockwise), \[2\times {{10}^{-4}}\,A\](Clockwise) done clear
  B)
  \[{{10}^{-4}}A\](Anticlockwise),\[2\times {{10}^{-4}}\,A\](Clockwise) done clear
  C)
  \[2\times {{10}^{-4}}\,A\](clockwise),\[{{10}^{-4}}\,A\](anticlockwise) done clear
  D)
  \[2\times {{10}^{-4}}\,A\](anticlockwise),\[{{10}^{-4}}A\](anticlockwise)   done clear
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• question_answer3)
  A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be
  A)
  Halved              done clear
  B)
  The same done clear
  C)
  Doubled             done clear
  D)
  Quadrupled done clear
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• question_answer4)
  The diagram shows a capacitor C and a resistor R connected in series to an ac source. \[{{V}_{1}}\] and \[{{V}_{2}}\] are voltmeters and A is an ammeter Consider now the following statements

  I. Readings in A and \[{{V}_{2}}\] are always in phase

  II. Reading in \[{{V}_{1}}\] is ahead in phase with reading in\[{{V}_{2}}\]

  III. Readings in A and \[{{V}_{1}}\] are always in phase which of these statements are/is correct

   
  A)
  I only    done clear
  B)
  II only done clear
  C)
  I and II only       done clear
  D)
  II and III only done clear
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• question_answer5)
  An equilateral triangular loop ADC having some resistance is pulled with a constant velocity v out of a uniform magnetic field directed into the paper (figure). At time t = 0, side DC of the loop is at edge of the magnetic field. The induced current (i) versus time (t) graph will be as
  A)
       done clear
  B)
  done clear
  C)
       done clear
  D)
  done clear
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• question_answer6)
  A conducting rod PQ of length \[l\] = 2 m is moving at a speed of \[2\,m{{s}^{-1}}\] making an angle of \[30{}^\circ \] with its length. A uniform magnetic field B = 2 T exists in a direction perpendicular to the plane of motion. Then
  A)
  \[{{V}_{p}}-{{V}_{Q}}=8V\] done clear
  B)
  \[{{V}_{p}}-{{V}_{Q}}=4V\] done clear
  C)
  \[{{V}_{Q}}-{{V}_{P}}=8V\] done clear
  D)
  \[{{V}_{Q}}-{{V}_{P}}=4V\] done clear
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• question_answer7)
  A conductor of length \[l\] and mass m can slide without any friction along the two vertical conductors connected at the top through a capacitor (figure). A uniform magnetic field B is set \[\bot \]up 1 to the plane of paper. The acceleration of the  conductor
  A)
  Is constant         done clear
  B)
  Increases done clear
  C)
  Decreases           done clear
  D)
  Cannot say done clear
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• question_answer8)
  A conducting ring of radius r is rolling without slipping with a constant angular velocity \[\omega \](figure). If the magnetic field strength is B and is directed into the page then the emf induced across PQ is
  A)
  \[B\omega {{r}^{2}}\]  done clear
  B)
  \[\frac{B\omega {{r}^{2}}}{2}\] done clear
  C)
  \[4B\omega {{r}^{2}}\] done clear
  D)
  \[\frac{{{\pi }^{2}}{{r}^{2}}B\omega }{8}\] done clear
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• question_answer9)
  Two resistors of 10\[\Omega \] and 20\[\Omega \] and an ideal inductor of 10 H are connected to a 2 V battery as shown in figure. Key K is inserted at time t = 0. The initial (t = 0) and final (\[t\to \infty \]) currents through the battery are
  A)
  \[\frac{1}{15}A,\frac{1}{10}A\]  done clear
  B)
  \[\frac{1}{10}A,\frac{1}{15}A\] done clear
  C)
  \[\frac{2}{15}A,\frac{1}{10}A\]  done clear
  D)
  \[\frac{1}{15}A,\frac{2}{25}A\] done clear
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• question_answer10)
  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)
  0.3s                  done clear
  B)
  0.15s done clear
  C)
  0.1 s                 done clear
  D)
  0.05s done clear
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• question_answer11)
  A metal conductor of length 1 m rotates vertically about one of its ends at an angular velocity 5 radians per second. If the horizontal component of the earth's magnetic field is\[0.2\times {{10}^{-4}}T\], then the emf developed between the two ends of the conductor is
  A)
  \[5\,\mu V\]        done clear
  B)
  \[50\,\mu V\] done clear
  C)
  \[5\,mV\]           done clear
  D)
  \[50\,mV\] done clear
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• question_answer12)
  A fully charged capacitor C with initial charge \[{{q}_{0}}\] is connected to a coil of self-inductance L at t = 0. The time at which the energy is stored equally between the electric and the magnetic fields is
  A)
  \[\pi \sqrt{LC}\]  done clear
  B)
  \[\frac{\pi }{4}\sqrt{LC}\] done clear
  C)
  \[2\pi \sqrt{LC}\]            done clear
  D)
  \[\sqrt{LC}\] done clear
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• question_answer13)
  In an AC circuit, the voltage applied is\[E={{E}_{0}}\sin \omega t\]. The resulting current in the circuit is\[I={{I}_{0}}\sin (\omega t-\pi /2)\]. The power consumption in the circuit is given by
  A)
  \[P=0\]  done clear
  B)
  \[P=\frac{{{E}_{0}}{{I}_{0}}}{2}\] done clear
  C)
  \[P=\sqrt{2}\]\[{{E}_{0}}{{I}_{0}}\]                 done clear
  D)
  \[P=\frac{{{E}_{0}}{{I}_{0}}}{\sqrt{2}}\] done clear
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• question_answer14)
  A 300\[\Omega \]. resistor is connected in series with a parallel-plate capacitor across the terminals of a 50.0 Hz ac generator. When the gap between the plates is empty, its capacitance is\[70/22\mu F\]. The ratio of the rms current in the circuit when the capacitor is empty to that when ruby mica of dielectric constant k = 5.0 is inserted between the plates, is equal to
  A)
  0.1                                done clear
  B)
  0.3 done clear
  C)
  0.6                    done clear
  D)
  2.9 done clear
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• question_answer15)
  A resistance of 20\[\Omega \] is connected to a source of an alternating potential V= 220\[\sin (100\pi t)\]. The time taken by the current to change from the peak value to rms value, is
  A)
  \[0.2\,s\] done clear
  B)
  \[0.25\,s\] done clear
  C)
  \[0.25\times {{10}^{-3}}\,s\]     done clear
  D)
  \[0.25\times {{10}^{-3}}\,s\] done clear
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• question_answer16)
  The self-inductance of a choke coil is 10 mH. When it is connected with a 10 V dc source, then the loss of power is 20 watt. When it is connected with 10 volt ac source loss of power is 10 watt. The frequency of ac source will be
  A)
  50 Hz    done clear
  B)
  60 Hz done clear
  C)
  80 Hz    done clear
  D)
  100 Hz done clear
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• question_answer17)
  PQ is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is.
  A)
  \[\frac{1}{vR}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\]           done clear
  B)
  \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{1}{vR}\] done clear
  C)
  \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{v}{R}\] done clear
  D)
  \[\frac{v}{R}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\] done clear
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• question_answer18)
  A horizontal ring of radius \[r=1/2m\] is kept in a vertical constant magnetic field 1 T. The ring is collapsed from maximum area to zero area in 1 s. Then the emf induced in the ring is
  A)
  \[1\,V\]              done clear
  B)
  \[(\pi /4)\,V\] done clear
  C)
  \[(\pi /2)\,V\]       done clear
  D)
  \[\pi \,V\] done clear
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• question_answer19)
  A wire is sliding as shown in figure. The angle between the acceleration and the velocity of the wire is
  A)
  \[30{}^\circ \]               done clear
  B)
  \[40{}^\circ \] done clear
  C)
  \[120{}^\circ \] done clear
  D)
  \[90{}^\circ \] done clear
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• question_answer20)
  A typical light dimmer used to dim the stage lights in a theatre consists of a variable induction for L (where inductance is adjustable between zero and\[{{L}_{\max }}\] connected in series with a light bulb B as shown. The mains electrical supply is 220 V a 50 Hz, the light bulb is rated at 220 V, 1100 W. What \[{{L}_{\max }}\]is required if the rate of energy dissipation in to mains the light bulb is to be varied by a factor of 5 from its upper limit of 1100W?
  A)
  0.69 H  done clear
  B)
  0.28 H done clear
  C)
  0.38 H  done clear
  D)
  0.56 H done clear
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• question_answer21)
  An ac source of angular frequency \[\omega \] is fed across a resistor r and a capacitor C in series. The current registered is\[I\]. If now the frequency of source is changed to \[\omega /3\] (but maintaining the same voltage), the current in then circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency\[\omega \].
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• question_answer22)
  A plane loop, shaped as two squares of sides a = 1 m and b = 0.4 m is introduced into a uniform magnetic field\[\bot \] to the plane of loop (figure). The magnetic field X. varies as\[B={{10}^{-3\,}}\sin \,(100t)\,T\]. The amplitude of the current induced (in A) in the loop if its resistance per unit length is \[r=5\,m\Omega {{m}^{-1}}\] is ________.
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• question_answer23)
  A long solenoid having 200 turns per centimeter carries a current of 1.5 A. At the center of the solenoid is placed a coil of 100 turns of cross-sectional area \[3.14\times {{10}^{-4}}{{m}^{2}}\] having its axis parallel to the field produced by the solenoid. When the direction of current in the solenoid is reversed within 0.05 s, the induced emf (in V) in the coil I is_______.
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• question_answer24)
  An emf of 96.0 mV is induced in the windings of a coil when the current in a nearby coil is increasing at the rate of 1.20 A/s. The mutual inductance (in mH) of the two coils is_______.
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• question_answer25)
  An ideal choke takes a current of 10 A when connected to an ac supply of 125 V and 50 Hz. A pure resistor under the same conditions takes a current of 12.5 A. If the two are connected to an ac supply of 100 V and 40 Hz, then the current (in A) in series combination of above resistor and inductor is _______.
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