# Solved papers for NEET Physics Electro Magnetic Induction NEET PYQ-Electro Magnetic Induction

### done NEET PYQ-Electro Magnetic Induction Total Questions - 30

• question_answer1) Two coils have a mutual inductance of 0.005 H. The current changes in the first coil according to equation $I={{I}_{0}}\,\sin \omega t,$ where ${{I}_{0}}=10\,A$ and $\omega =100\,\pi$ rad/s. The maximum value of emf in the second coil is:                                                                                                                         [AIPMT 1998]

A)
$2\,\pi$

B)
$5\,\pi$

C)
$\pi$

D)
$4\,\pi$

• question_answer2) A step-up transformer operates on a 230 V line and supplies current of 2 A to a load. The ratio of the primary and secondary windings is 1 :  25. The current in the primary coil is:                                                           [AIPMT 1998]

A)
15 A

B)
50 A

C)
25 A

D)
12.5 A

• question_answer3)  In a circuit inductance L and capacitance C are connected as shown in figure. ${{A}_{1}}$ and ${{A}_{2}}$ are ammeters. When key K. is pressed to complete the circuit, then just after closing key (K), the reading of current will be:                                                                                                                     [AIPMT 1999]

A)
zero in both ${{A}_{1}}$ and ${{A}_{2}}$

B)
maximum in both ${{A}_{1}}$ and ${{A}_{2}}$

C)
zero in ${{A}_{1}}$ and maximum in ${{A}_{2}}$

D)
maximum in ${{A}_{1}}$ and zero in ${{A}_{2}}$

• question_answer4) In an inductor of self-inductance $L=2\,mH,$ current changes with time according to relation $i={{t}^{2}}{{e}^{-t}}\,$. At what time emf is zero?                                                                                                 [AIPMT 2001]

A)
4 s

B)
3 s

C)
2 s

D)
1 s

• question_answer5) A coil of 40 H inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 V battery. The time constant of the circuit is:                                  [AIPMT (S) 2004]

A)
5 s

B)
1/5 s

C)
40 s

D)
20 s

• question_answer6) The magnetic flux through a circuit of resistance R changes by an amount $\Delta \phi$ in a time $\Delta t$. Then the total quantity of electric charge Q that passes any point in the circuit during the time $\Delta t$ is represented by:                                                                                                                                     [AIPMT (S) 2004]

A)
$Q=\frac{1}{R},\frac{\Delta \phi }{\Delta t}$

B)
$Q=\frac{\Delta \phi }{R}$

C)
$Q=\frac{\Delta \phi }{\Delta t}$

D)
$Q=R\,\,.\frac{\Delta \phi }{\Delta t}$

• question_answer7) The core of a transformer is laminated because:                                          [AIPMT (S) 2006]

A)
energy losses due to eddy currents may be minimised.

B)
the weight of the transformer may be reduced

C)
rusting of the core may be prevented

D)
ratio of voltage in primary and secondary may be increased

• question_answer8) Two coils of self-inductances 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is:            [AIPMT (S) 2006]

A)
10 mH

B)
6 mH

C)
4 mH

D)
16 mH

• question_answer9) The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux $\phi$ linked with the primary coil is given by $\phi ={{\phi }_{0}}+4t,$ where $\phi$ is in weber, t is time in second and ${{\phi }_{0}}$ is a constant, the output voltage across the secondary coil is: [AIPMT (S) 2007]

A)
90 V

B)
120 V

C)
220 V

D)
30 V

• question_answer10) A transformer is used to light a 100 W and 110 W lamp from a 220 W mains. If the main current is 0.5 A, the efficiency of the transformer is approximately:                      [AIPMT (S) 2007]

A)
30%

B)
50%

C)
90%

D)
10%

• question_answer11) A long solenoid has 500 rums. When a current of 2 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is $4\times {{10}^{-3}}\,Wb$. The self-inductance of the solenoid is          [AIPMPT (S) 2008]

A)
2.5 H

B)
2.0 H

C)
1.0 H

D)
4.0 H

• question_answer12) A conducting circular loop is placed in a uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at $2\,\,mm{{s}^{-1}}$. The induced emf in the loop when the radius is 2 cm is [AIPMT (S) 2009]

A)
$3.2\,\,\pi \mu V$

B)
$4.8\,\,\pi \mu V$

C)
$0.8\,\,\pi \mu V$

D)
$1.6\,\,\pi \mu V$

• question_answer13) A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the efficiency of the transformer is 80%, the current drawn by the primary windings of the transformer is          [AIPMT (S) 2010]

A)
3.6 A

B)
2.8 A

C)
2.5 A

D)
5.0 A

• question_answer14) A condenser of capacity C is charged to a potential difference of ${{V}_{1}}$. The plates of the condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser reduces to ${{V}_{2}}$ is                                                         [AIPMT (M) 2010]

A)
${{\left( \frac{C{{({{V}_{1}}-{{V}_{2}})}^{2}}}{L} \right)}^{\frac{1}{2}}}$

B)
$\frac{C(V_{1}^{2}-V_{2}^{2})}{L}$

C)
$\frac{C(V_{1}^{2}+V_{2}^{2})}{L}$

D)
None of these

• question_answer15)  The current; in a coil varies with time as shown in the figure. The variation of induced emf with time would be

A)

B)

C)

D)

• question_answer16) A body of mass M hits normally a rigid wall with velocity v and bounces back with the same velocity. The impulse experienced by the body is                                                                                        [AIPMT (S) 2011]

A)
1.5 Mv

B)
2 Mv

C)
zero

D)
Mv

• question_answer17)  In a coil of resistance $10\,\,\Omega ,$ the induced   2 current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in weber is [AIPMT (M) 2012]

A)
8

B)
2

C)
6

D)
4

• question_answer18) A coil of resistance $400\,\Omega$ is placed in a magnetic field. If the magnetic flux $\phi$ (Wb) linked with the coil varies with time t (sec) as $\phi =50\,{{t}^{2}}+4$. The current in the coil at $t=2s$ is               [AIPMT (S) 2012]

A)
0.5 A

B)
0.1 A

C)
2 A

D)
1 A

•  The current (I) in the inductance is varying with time according to the plot shown in figure. [AIPMT (S) 2012] Which one of the following is the correct variation of voltage with time in the coil?

A)

B)

C)

D)

• question_answer20) A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is     [NEET 2013]

A)
once per revolution

B)
twice per revolution

C)
four times per revolution

D)
six times per revolution

• question_answer21) A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are  [NEET 2014]

A)
300 V, 15 A

B)
450 V, 15 A

C)
450 V, 13.5 A

D)
600 V, 15 A

• question_answer22)  A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is u, is                     [NEET 2014]

A)
zero

B)
$Bv\pi {{r}^{2}}/2$ and P is at higher potential

C)
$\pi rBv$ and R is at higher potential

D)
$2\,rBv$ and R is at higher potential

• question_answer23)  A conducting square frame of side $'a'$ and a long straight wire carrying current $I$ are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity V. The emf induced in the frame will be proportional to [NEET  2015]

A)
$\frac{1}{{{x}^{2}}}$

B)
$\frac{1}{{{(2x-a)}^{2}}}$

C)
$\frac{1}{{{(2x+a)}^{2}}}$

D)
$\frac{1}{(2x+a)(2x+a)}$

• question_answer24)  An electron moves on a straight line path XY as shown. The abed is a coil adjacent in the path of electron. What will be the direction of current, if any induced in the coil?             [NEET (Re) 2015]

A)
abcd

B)

C)
The current will reverse its direction as the electron goes past the coil

D)
No current induced

• question_answer25) A long solenoid has 1000 turns. When a current of 4A flows through it, the magnetic flux linked with each turn of the solenoid is $4\times {{10}^{-3}}\,Wb$. The self-inductance of the solenoid is               [NEET - 2016]

A)
4 H

B)
3 H

C)
2 H

D)
1 H

• question_answer26)  Figure shows a circuit contains three identical resistors with resistance $R=9.0\,\,\Omega$ each, two identical inductors with inductance $L=2.0\text{ }mH$ each, and an ideal battery with emf $\varepsilon =18\,V$. The current $'i'$ through the battery just after the switch closed is                                                                       [NEET-2017]

A)
0 ampere

B)
2 mA

C)
0.2 A

D)
2 A

• question_answer27) A long solenoid of diameter $0.1\text{ }m$ has $2\times {{10}^{4}}$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is $10\,{{\pi }^{2}}\Omega ,$ the total charge flowing through the coil during this time is                                     [NEET-2017]

A)
$16\pi \,\mu C$

B)
$32\,\,\pi \,\mu C$

C)
$16\mu C$

D)
$32\,\mu C$

• question_answer28) The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance                                                                                         [NEET - 2018]

A)
1.389 H

B)
138.88 H

C)
0.138 H

D)
13.89 H

• question_answer29) A 800 turn coil of effective area $0.05\text{ }{{m}^{2}}$is kept perpendicular to a magnetic field$5\times {{10}^{5}}T$. When the plane of the coil is rotated by 90º around any of its coplanar axis in 0.1 s, the emf induced in the coil will be:           [NEET 2019]

A)
$2\times {{10}^{3}}\text{ }V$

B)
0.02 V

C)
2 V

D)
0.2 V

• question_answer30) In which of the following devices, the eddy current effect is not used?                        [NEET 2019]

A)
Electromagnet

B)
Electric heater

C)
Induction furnace

D)
Magnetic braking in train