Electromagnetic Induction PYQs Set 7 (PDF)

Set 7 of 10 · Questions 181-210 of 274

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Induction · Set 7 (Q181-210)
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181. $The current (I) in the inductance is varying with time according to the plot shown in figure. Which one of the following is the correct variation of voltage with time in the coil?$ (1) (2) (3) (4) 182. $There are two long co-axial solenoids of same length l. The inner and outer coils have radii r_{1} and r_{2} and number of turns per unit length n_{1} and n_{2}, respectively. The ratio of mutual inductance to the self-inductance of the inner-coil is:$ (1) $\frac{n _{2}}{n _{1}} . \frac{r _{2}^{2}}{r _{1}^{2}}$ (2) $\frac{n _{2}}{n _{1}}$ (3) $\frac{n _{1}}{n _{2}}$ (4) $\frac{n _{2}}{n _{1}} . \frac{r _{1}}{r _{2}}$ 183. $An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?$ (1) $The current will reverse its direction as the electron goes past the coil$ (2) $No current induced$ (3) $abcd$ (4) $adcb$ 184. $Two concentric coplanar circular conducting loops have radii R and r (R ≫ r) . Their mutual inductance is proportional to$ (1) $\frac{r}{R}$ (2) $\frac{R}{r}$ (3) $\frac{r ^{2}}{R}$ (4) $\frac{R ^{2}}{r}$ 185. $Some magnetic flux is changed from a coil of resistance 10 ohm. As a result an induced current is developed in it, which varies with time as shown in figure. The magnitude of change in flux through the coil in weber is$ (1) $2$ (2) $4$ (3) $6$ (4) $None of these$ 186. $A circular coil of area 100 cm^{2} and 20 turns is kept in magnetic field of flux density 2 Wb - m^{2} . It rotates from a position where its plane makes an angle of 30^{\circ} with the field to a position perpendicular to the field in a time 0.2 s. Find the magnitude of the emf induced in the coil due to its rotation.$ (1) $2 V$ (2) $3 V$ (3) $1.5 V$ (4) $1 V$ 187. $A square loop of side 20cm and resistance 1Ω is moved towards right with a constant speed υ_{0} . The right arm of the loop is in a uniform magnetic field of 5T. The field is perpendicular to the plane of the loop and is going into it. The loop is connected to a network of resistors each of value 4Ω . What should be the value of v_{0} so that a steady current of 2mA flows in the loop?$ (1) $1 m/s$ (2) $1cm/s$ (3) $102 m/s$ (4) $10-2 cm/s$ 188. $The arm PQ of a rectangular conductor is moving from x = 0 to x = 2b outwards and then inwards from x = 2b to x = 0 as shown in the figure. A uniform magnetic field perpendicular to the plane is acting from x = 0 to x = b. Identify the graph showing the variation of different quantities with distance:$ (1) $A-Flux, B-Power dissipated, C-EMF$ (2) $A-Power dissipated, B-Flux, C-EMF$ (3) $A-Flux, B-EMF, C-Power dissipated$ (4) $A-EMF, B-Power dissipated, C-Flux$ 189. $Two coils of self inductance L_{1} and L_{2} are connected in series combination having mutual inductance of the coils as M. The equivalent self inductance of the combination will be:$ (1) $\frac{1}{L _{1}} + \frac{1}{L _{2}} + \frac{1}{M}$ (2) $L_{1} + L_{2} + M$ (3) $L_{1} + L_{2} + 2M$ (4) $L_{1} + L_{2} - 2M$ 190. $As shown in the figure, a battery of emf ε is connected to an inductor L and resistance R in series. The switch is closed at t = 0. The total charge that flows from the battery, between t = 0 and t = t_{c} (t_{c} is the time constant of the circuit) is:$ (1) $\frac{ϵ L}{R ^{2}} (1 - \frac{1}{e})$ (2) $\frac{ϵ R}{e L ^{2}}$ (3) $\frac{ϵ L}{R ^{2}}$ (4) $\frac{ϵ L}{e R ^{2}}$ 191. $For the given circuit the current i through the battery when the key in closed and the steady state has been reached is .......$ (1) $6A$ (2) $25A$ (3) $10A$ (4) $0A$ 192. $Near a circular loop of conducting wire as shown in the figure an electron moves along a straight line. The direction of the induced current if any in the loop is$ (1) $variable$ (2) $clockwise$ (3) $anticlockwise$ (4) $zero.$ 193. $A 1 m long metal rod AB completes the circuit as shown in figure. The area of circuit is perpendicular to the magnetic field of 0.10 T. If the resistance of the total circuit is 2Ω then the force needed to move the rod towards right with constant speed (v) of 1.5 m / s is____N.$ (1) $5.7 \times 10^{- 2}$ (2) $7.5 \times 10^{- 2}$ (3) $7.5 \times 10^{- 3}$ (4) $5.7 \times 10^{- 3}$ 194. $There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then$ (1) $current is induced in the loop in the anticlockwise direction$ (2) $current is induced in the loop in the clockwise direction$ (3) $AC is induced in the loop$ (4) $no current is induced in the loop.$ 195. $A L C R circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant b, the correct equivalence would be:$ (1) $L \Leftrightarrow \frac{1}{b}, C \Leftrightarrow \frac{1}{m}, R \Leftrightarrow \frac{1}{k}$ (2) $L \Leftrightarrow k, C \Leftrightarrow b, R \Leftrightarrow m$ (3) $L \Leftrightarrow m, C \Leftrightarrow \frac{1}{k}, R \Leftrightarrow b$ (4) $L \Leftrightarrow m, C \Leftrightarrow k, R \Leftrightarrow b$ 196. $A cycle wheel of radius 0.5 m is rotated with constant angular velocity of 10 rad / s in a region of magnetic field of 0.1 T which is perpendicular to the plane of the wheel. The emf generated between its center and the rim is [NEET 2019]$ (1) $0.25 V$ (2) $0.125 V$ (3) $0.5 V$ (4) $zero$ 197. $At time t = 0 magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5 s, then induced EMF in the loop is:$ (1) $28 µV$ (2) $36 µV$ (3) $48 µV$ (4) $56 µV$ 198. $Two straight conducting rails form a right angle as shown below. A conducting bar in contact with the rails starts at the vertex at time t = 0 and moves with constant velocity of v = 5 m / s along them. A magnetic field with B = 0.1 T is directed out of the page. The absolute value of the emf around the triangle at the time t = 4 s will be$ (1) $10 V$ (2) $15 V$ (3) $20 V$ (4) $30 V$ 199. $A rod of length 2 m slides with a speed of 5 m s^{- 1} on a rectangular conducting frame as shown in figure. There exists a uniform magnetic field of 0.04 T perpendicular to the plane of the figure. If the resistance of the rod is 3Ω . The current through the rod is$ (1) $0.75 A$ (2) $1.33 A$ (3) $75 mA$ (4) $133 mA$ 200. $Consider a toroid with rectangular cross section, of inner radius a, outer radius b and height h, carrying n number of turns: Then the self-inductance of the toroidal coil when current I passing through the toroid is$ (1) $\frac{μ _{0} n ^{2} h}{2 π} ln (\frac{b}{a})$ (2) $\frac{μ _{0} nh}{2 π} ln (\frac{b}{a})$ (3) $\frac{μ _{0} n ^{2} h}{2 π} ln (\frac{a}{b})$ (4) $\frac{μ _{0} nh}{2 π} ln (\frac{a}{b})$ 201. $A simple pendulum with bob of mass ' m' and conducting wire of length ' L' swings under gravity through an angle ' θ'. The component of earth's magnetic field in the direction perpendicular to swing is ' B'. Maximum e.m.f. induced across the pendulum is (g = acceleration due to gravity)$ (1) $2 BLsin (\frac{θ}{2}) (gL)^{1/2}$ (2) $BLsin (\frac{θ}{2}) (gL)$ (3) $2 BLsin (\frac{θ}{2}) (gL)^{3/2}$ (4) $2 BLsin (\frac{θ}{2}) (gL)^{2}$ 202. $In the given circuit the reading of voltmeter V_{1} and V_{2} are 300 volts each. The reading of the voltmeter V_{3} and ammeter A are respectively$ (1) $150 V, 2.2 A$ (2) $220 V, 2.2 A$ (3) $220 V, 2.0 A$ (4) $100 V, 2.0 A$ 203. $A small bar magnet is moved through a coil at constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer G attached across the coil? Three positions shown describe : (a) the magnet's entry (b) magnet is completely inside and (c) magnet's exit.$ (1) (2) (3) (4) 204. $A square loop of side 2 cm enters a magnetic field with a constant speed of 2 cm s^{- 1} as shown. The front edge enters the field at t = 0 s . Which of the following graph will correctly depicts the induced emf in the loop? [Take clockwise direction positive]$ (1) (2) (3) (4) 205. $In the circuit given in figure, 1 and 2 are ammeters. Just after key K is pressed to complete the circuit, the reading will be$ (1) $zero in 1, maximum in 2$ (2) $maximum in both 1 and 2$ (3) $zero in both 1 and 2$ (4) $maximum in 1, zero in 2.$ 206. $A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure. The potential difference developed across the ring when its speed is v,$ (1) $zero$ (2) $\frac{Bvπ r ^{2}}{2} and P is at higher potential$ (3) $πrBv and R is at higher potential$ (4) $2 rBv and R is at higher potential$ 207. $A long solenoid of radius R carries a time dependent current I = I_{0} t (1 - t) . A ring of radius 2 R is placed coaxially near its centre. During the time interval 0 \leq t \leq 1, the induced current I_{R} and the induced emf V_{R} in the ring vary as:$ (1) $current will change its direction and its emf will be zero at t = 0.25 sec$ (2) $current will not change its direction & emf will be maximum at t = 0.5 sec$ (3) $current will not change direction and emf will be zero at 0.25 sec .$ (4) $At t = 0.5 direction of I_{R} reverses and V_{R} is zero$ 208. $The figure shows a square loop L of side 5 cm which is connected to a network of resistances. The whole setup is moving towards right with a constant speed of 1 cms^{- 1} . At some instant, a part of L is in a uniform magnetic field of 1T, perpendicular to the plane of the loop. If the resistance of L is 1.7Ω, the current in the loop at that instant will be close to:$ (1) $60 μA$ (2) $170 μA$ (3) $150 μA$ (4) $115 μA$ 209. $An aeroplane, with its wings spread 10m, is flying at a speed of 180km/h in a horizontal direction. The total intensity of earth's field at that part is 2.5 \times 10^{- 4} Wb / m^{2} and the angle of dip is 60°. The emf induced between the tips of the plane wings will be?$ (1) $88.37 mV$ (2) $62.50m V$ (3) $54.125 mV$ (4) $108.25 mV$ 210. $A copper wire is wound on a wooden frame, whose shape is that of a square if each side of the frame is increased by a factor of 3 , keeping the number of turns of the coil per unit length of the frame the same, then the self-inductance of the coil:$ (1) $increases by a factor of 3$ (2) $decreases by a factor of 93$ (3) $increases by a factor of 27$ (4) $decreases by a factor of 9$