Electromagnetic Induction PYQs Set 8 (PDF)

Set 8 of 10 · Questions 211-240 of 274

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Induction · Set 8 (Q211-240)
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211. $As shown in the figure, a battery of emf ϵ is connected to an inductor L and resistance R in series. The switch is closed at t = 0 . The total charge that flows from the battery, between t = 0 and t = t_{c} (t_{c} is the time constant of the circuit) is$ (1) $\frac{ϵ L}{R ^{2} e}$ (2) $\frac{ϵ L}{R ^{2}}$ (3) $\frac{ϵ L ( 1 - \frac{1}{e} )}{R}$ (4) $\frac{ϵ L}{R}$ 212. $An elliptical loop having resistance R, of semi major axis a, and semi minor axis b is placed in a magnetic field as shown in the figure. If the loop is rotated about the x -axis with angular frequency ω, the average power loss in the loop due to Joule heating is$ (1) $\frac{πabBω}{R}$ (2) $\frac{π ^{2} a ^{2} b ^{2} B ^{2} ω ^{2}}{2 R}$ (3) $Zero$ (4) $\frac{π ^{2} a ^{2} b ^{2} B ^{2} ω ^{2}}{R}$ 213. $At time t = 0 magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5 s, then induced EMF in the loop is:$ (1) $56 μV$ (2) $28 μV$ (3) $30 μV$ (4) $48 μV$ 214. $An inductor of inductance L = 400 mH and resistors of resistances R_{1} = 2 Ω and R_{2} = 2 Ω are connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. The potential drop across L as a function of time is:$ (1) $\frac{12}{t} e^{- 3 t} V$ (2) $6 (1 - e^{- t /0.2}) V$ (3) $12 e^{-5 t} V$ (4) $6 e^{-5 t} V$ 215. $In the above figure, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively are through the directions [NEET 2024]$ (1) $AB and DC$ (2) $BA and CD$ (3) $AB and CD$ (4) $BA and DC$ 216. $In the circuit shown here, the point 'C' is kept connected to point 'A' till the current flowing through the circuit becomes constant. Afterward, suddenly point 'C' is disconnected from point 'A' and connected to point 'B' at time t = 0. Ratio of the voltage across resistance and the inductor at t = L/R will be equal to:$ (1) $\frac{e}{1 - e}$ (2) $1$ (3) $-1$ (4) $\frac{1 - e}{e}$ 217. $A series R‐C circuit is connected to an alternating voltage source. Consider two situations: (i) When capacitor is air filled. (ii) When capacitor is mica filled. Current through resistor is i and voltage across capacitor is V then$ (1) $i_{a} = i_{b}$ (2) $V_{a} = V_{b}$ (3) $V_{a} < V_{b}$ (4) $V_{a} > V_{b}$ 218. $A beam of light travelling along X-axis is described by the electric field E_{y} = 900 sin ω (t-x/c). The ratio of electric force to magnetic force on a charge q moving along Y-axis with a speed of 3 x 107 ms-1 will be: [Given speed of light = 3 x 108 ms-1]$ (1) $1 : 1$ (2) $1 : 10$ (3) $10 : 1$ (4) $l : 2$ 219. $A square loop of side 15 cm being moved towards right at a constant speed of 2 cm / s as shown in figure. The front edge enters the 50 cm wide magnetic field at t = 0 . The value of induced emf in the loop at t = 10 s will be:$ (1) $0.3 mV$ (2) $zero$ (3) $4.5 mV$ (4) $3 mV$ 220. $Consider the LR circuit shown in the figure. If the switch S is closed at t = 0 then the amount of charge that passes through the battery between t = 0 and t = \frac{L}{R} is:$ (1) $\frac{2.7 EL}{R ^{2}}$ (2) $\frac{EL}{2.7 R ^{2}}$ (3) $\frac{7.3 EL}{R ^{2}}$ (4) $\frac{EL}{7.3 R ^{2}}$ 221. $An aircraft with a wingspan of 40 m flies with a speed of 1080 km / hr in the eastward direction at a constant altitude in the northern hemisphere, where the vertical component of the earth's magnetic field 1.75 \times 10^{- 5} T . Then the emf developed between the tips of the wings is$ (1) $0.34 V$ (2) $2.1 V$ (3) $0.5 V$ (4) $0.21 V$ 222. $The magnetic flux through the triangular loop shown in the figure below: where a uniform magnetic field of strength 2 T points perpendicularly into the plane of the triangle.$ (1) $10^{- 4} Wb$ (2) $2\times 1 0^{- 4} Wb$ (3) $1 Wb$ (4) $2 Wb$ 223. $A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is$ (1) $four times per revolution$ (2) $six times per revolution$ (3) $once per revolution$ (4) $twice per revolution$ 224. $A coil of self-inductance 10 mH and resistance 0.1 Ω is connected through a switch to a battery of internal resistance 0.9 Ω. After the switch is closed, the time taken for the current to attain 80% of the saturation value is: [Take ln 5 = 1.6]$ (1) $0.324 s$ (2) $0.103 s$ (3) $0.002 s$ (4) $0.016 s$ 225. $A rectangular metallic loop is moving out of a uniform magnetic field region to a field free region with a constant speed. When the loop is partially inside the magnate field, the plot of magnitude of induced emf (ϵ) with time (t) is given by$ (1) (2) (3) (4) 226. $The current i in a coil varies with time as shown in the figure. The variation of induced emf with time would be$ (1) (2) (3) (4) 227. $A bar magnet is allowed to fall vertically through a copper coil placed in a horizontal plane. The magnet falls with a net acceleration$ (1) $= g$ (2) $Zero$ (3) $< g$ (4) $> g$ 228. $In a coil of resistance10 Ω, the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in weber is$ (1) $8$ (2) $2$ (3) $6$ (4) $4$ 229. $A small square loop of wire of side l is placed inside a large square loop of wire L (L >> I). Both loops are coplanar and their centers coincide at point O as shown in figure. The mutual inductance of the system is:$ (1) $\frac{2 2 μ _{0} L ^{2}}{πl}$ (2) $\frac{μ _{0} l ^{2}}{2 2 πL}$ (3) $\frac{2 2 μ _{0} l ^{2}}{πL}$ (4) $\frac{μ _{0} L ^{2}}{2 2 πl}$ 230. $Two conducting circular loops A and B are placed in the same plane with their centers coincidng as shown in figure. The mutual inductance between them is:$ (1) $\frac{μ _{0} π b ^{2}}{2 a}$ (2) $\frac{μ _{o}}{2 π} \cdot \frac{b ^{2}}{a}$ (3) $\frac{μ _{0}}{2 π} \cdot \frac{a ^{2}}{b}$ (4) $\frac{μ _{0} π a ^{2}}{2 b}$ 231. $The r.m.s. value of potential difference V shown in the figure is$ (1) $\frac{V _{0}}{3}$ (2) $V_{0}$ (3) $\frac{V _{0}}{2}$ (4) $\frac{V _{0}}{2}$ 232. $A coil of area A and N turns is rotating with angular velocity ω in a uniform magnetic field B about an axis perpendicular to B . Magnetic flux ϕ and induced emf ϵ across it, at an instant when B is parallel to the plane of coil, are:$ (1) $ϕ = AB, ϵ = 0$ (2) $ϕ = 0, ϵ = 0$ (3) $ϕ = 0, ϵ = NABω$ (4) $ϕ = AB, ϵ = NABω$ 233. $A long straight solenoid with cross-sectional radius a and number of turns per unit length n has a current varying with time as I (As^{- 1}) . The magnitude of the electric field as a function of distance r from the solenoid axis is$ (1) $\frac{n μ _{0} a ^{2} l}{2 r}$ (2) $\frac{μ _{0} ln}{2 a}$ (3) $\frac{n a ^{2} l}{2 μ _{0} r}$ (4) $\frac{μ _{0} la}{2 n}$ 234. $The current flowing through an inductance coil of self inductance 6 mH at different time instants is as shown. The emf induced between t = 20 s and t = 40 s is nearly$ (1) $2 \times 10^{- 2} V$ (2) $3 \times 10^{- 4} V$ (3) $4 \times 10^{- 3} V$ (4) $30 \times 10^{2} V$ 235. $A metallic rod of length ‘l’ is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ‘B’ in the region, the e.m.f. induced across the ends of the rod is:$ (1) $\frac{2 B ω l ^{2}}{2}$ (2) $\frac{3 B ω l ^{2}}{2}$ (3) $\frac{4 B ω l ^{2}}{2}$ (4) $\frac{5 B ω l ^{2}}{2}$ 236. $In a coil resistance 100Ω, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is:$ (1) $275 Wb$ (2) $200 Wb$ (3) $225 Wb$ (4) $250 Wb$ 237. $A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is:$ (1) $Zero$ (2) $B v π r^{2} /2 and P is at higher potential$ (3) $πrBv and R is at higher potential$ (4) $2rBv and R is at higher potential$ 238. $A cooper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per unit length of the frame the same, then the self inductance of the coil?$ (1) $Decrease by a factor of 9$ (2) $Increase by a factor of 27$ (3) $Decrease by a factor of 3$ (4) $Increases by a factor of 93$ 239. $A 20 Henry inductor coil is connected to a 10 ohm resistance in series as shown in figure. The time at which rate of dissipation of energy (joule's heat) across resistance is equal to the rate at which magnetic energy is stored in the inductor, is$ (1) $\frac{2}{ln 2}$ (2) $\frac{1}{2} ln 2$ (3) $2 ln 2$ (4) $ln 2$ 240. $A uniform magnetic field is restricted within a region of radius r . Ihe magnetic field changes with time at a rate \frac{d B}{dt} . Loop 1 of radius R > r encloses the region r and loop 2 of radius R is outside the region of magnetic field as shown in the figure. Then the e . m . f . generated is$ (1) $zero in loop 1 and zero in loop 2$ (2) $- \frac{d B}{dt} π r^{2} in loop 1 and - \frac{d B}{dt} π r^{2} in loop 2$ (3) $zero in loop 1 and - \frac{d B}{dt} π r^{2} in loop 2$ (4) $- \frac{d B}{dt} π r^{2} in loop 1 and zero in loop 2$