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The current, through a coil of self inductance. L = 2mH, is given by I = t2 e-t at time t. The time taken, to make the induced emf zero, will be (1) 1 S (2) 2 S (3) 3 S (4) 4 S

asked
Jan 13
by
anonymous

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**Description :** The current ‘i’ in a coil of self inductance 'l' varies with time as shown in figure. The variation of the induced emf 'ε' with time would than be represented by the graph labelled as graph (1) A (2) B (3) C (4) D

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**Description :** The magnetic flux, through a coil, present in a magnetic field, directed perpendicular to its plane, varies with time (in second) according to the relation. ϕB = 6t2 + 7t + 1 (ϕB in miliweber) Find the ... at t = 2s. Also find the current, and its direction, in the resistance R, if R = 10Ω

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**Description :** A very small circular loop of area 5 x 10-4m2 , resistance 2 ohm and negligible inductance, is initially coplanar and cocentric, with a much larger fixed circular loop of radius 0.1m. A constant ... diameter. Calculate the induced emf and induced current, as a function of time, in the smaller loop.

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**Description :** When the current in a coil changes from +2A to –2A in 0.05 second, an emf of 8V is induced in a coil. The coefficient of self induction of the coil is (1) 0.1 H (2) 0.2 H (3) 0.4 H (4) 0.8 H

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**Description :** A long solenoid of radius 0.01 m has 600 turns per meter. A smaller coil of 100 turns is wrapped closely around the centre of the bigger solenoid. If the current in the solenoid rises from zero to 2A in 1ms. Find the emf induced in smaller coil.

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**Description :** A conducting loop of area 5.0 cm2 is placed in a magnetic field which varies sinosoudally with time as B = B0 sin ωt where B0 = 0.20 T and ω 300/s, such that the normal to the coil makes an angle of 60° with ... ) the maximum emf induced in the coil (b) the emf induced at \(t =(\frac{\pi}{600})s.\)

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**Description :** A (infinite) long straight wire, carrying a current I, is placed parallel to the x-axis. If a straight conductor, of length l , positioned along the y-axis, as shown, starts moving with a uniform velocity v = v\(\hat{i}\) , the ... +\frac{l}{a})\) (4) \(\frac{μ_0Iv}{2\pi}\frac{l}{(a+\frac{l}{2})}\)

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**Description :** A pair of (insulated) coils having of n1 and n2 tunrs, are kept close together. When the current, passing through the first, is reduced at a rate r, an emf of 3mV is developed across the other coil. If the second coil were to ... across the first coil will be (1) 1.5 mV (2) 2.0 mV (3) 3 mV (4) 6 mV

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**Description :** A circular coil, of radius R, is set up with its plane in the yz plane; its centre at the origin and its axis along the x-axis. It carries a constant current I. A small rectangular lamina, of area ΔA , is set-up ... on x, is best represented by the graph, labelled as graph (1) P (2) Q (3) R (4) S

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**Description :** A 50 turns circular coil has as average a radius of 3 cm. It is kept in a magnetic field acting normal to the area of the coil. The magnetic field B is increased from (0.10 T) to (0.35 T) in 2 ms. The average induced emf in the coil, would be (1) 0.177 V (2) 1.77 V (3) 17.7 V (4) 177 V

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**Description :** A spring, of spring constant 100 N/M, is compressed through a distance of 4cm. The potential energy, stored in this compressed spring, equals the work done, by the source', in establishing a current of 2A in a given ... self inductance of the coil equals (1) 20 mH (2) 40 mH (3) 60 mH (4) 80 mH

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**Description :** A (long thin) solenoid core has an insulated primary coil, (of n1 turns per unit length) and an insulated secondary coil, (of n2 turns per unit length) wound on top of the primary coil. The cross sectional area of the solenoid, equals ... M = \((\frac{L^2_1}{L^2_2})\) (4) M = \((\frac{L^2_2}{L_1})\)

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**Description :** A coil of area 500 cm2 and 2000 turns is kept normal to a magnetic field of 4 x 10-5 Wb/m2 . It is rotated through 1800 in 0.1 second. (i) Calculate the average induced emf (ii) if the total resistance of circuit be 20 ohm, calculate the induced charge.

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**Description :** A circular ciol, of average radius R, having N turns and carrying a current I, is set-up, horizontally with its plane in the x-y plane and its axis along the z-axis, so shown. A small rectangular lamina of sides Δa and Δb , is set ... ) (4) \(\frac{(I)(Δa)(Δb)}{2Δt}N\frac{μ_0R^2I}{(R^2+z^2)^{3/2}}\)

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**Description :** A conducting circular loop of area 1 mm2 is placed coplanarly with a long, straight wire at a distance of 20 cm from it. The straight wire carries an electric current which changes from 10A to zero in 0.1s. Find the average emf induced in the loop in 0.1 s.

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**Description :** Induced emf in a planer coil,due to a change in its orientation in a uniform magnetic field.

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**Description :** A rectangular coil, of 300 turns, has an average area of 25 cm x 10 cm. The coil rotates, with a speed of 50 cycles per second, in a uniform magnetic field of 4 x 10-2T, about an axis perpendicular to the field. The peak value of induced emf (in volt), is (1) 3 π (2) 30 π (3) 300 π (4) 3000 π

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**Description :** A conducting circular loop is placed in a uniform magnetic field B = 0.25 T, with its plane perpendicular to the field. The radius of the loop is made to shrink at a constant rate of 1 mm/s. The induced emf, when the radius is 2 cm, ... })μV\) (2) \((\pi)μV\) (3) \((2\pi)μV\) (4) \((2.5)\pi μV\)

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**Description :** A magnetic field, directed along z axis, varies as B = B0 x/a. where a is a positive constant. A square loop (of side l ), made of copper, is placed with its edges parallel to the x and y axes. If the loop is made to move with a ... B0 V0 l (3) B0 V0 \(\frac{l^2}{2a}\) (4) B0 V0 \(\frac{l^3}{a^2}\)

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**Description :** An air cored coil has a self inductance of 0.1 H. A soft iron core of relative permability 1000 is introduced and the number of turns is reduced to 1/10th of the previous value. Find the new value of self inductance.

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**Description :** A conducting coil of 600 turns has a self inductance of 108 mH. The self inductance of a second identical coil, having of 500 turns, will be (1) 75 mH (2) 90 mH (3) 130 mH (4) 155 mH

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**Description :** Two (insulated) coils are wound, (one over the other), on a solenoid core. If the number of turns, per unit length, of the first coil and of the second coil, were to be increased by a factors of 3 and 4, respectively, the self ... , 4 and 12 (2) 3, 4 and 4/3 (3) 9, 16 and 16/9 (4) 9, 16 and 12

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**Description :** A (solenoid) coil is wound on a core of square cross-section. If all the linear dimensions of core are increased 2 times, but the number of turns per unit length of the coil, remains same, the self inductance would increases by a factor of (1) 2 (2) 4 (3) 8 (4) 16

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**Description :** The coefficient of mutual inductance of two circuits A and B is 3 mH and their respective resistances are 100 hm and 4 ohm. How much should the currents change, in 0.02 second, in circuit A, so that an induced current 0.006 ampere flows ... the circuit B? (1) 0.16 A (2) 0.18 A (3) 0.24 A (4) 1.6 A

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**Description :** A copper rod, of length 0.19m, kept parallel to a long straight wire carrying a current of 5A is with a uniform velocity of 10 m/s. The rod is perpendicular to the wire. The two ends of rod are at ... .01m and 0.2m, from the wire, (as shown in the figure). Calculate the emf induced in the rod.

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**Description :** A current of 4A flows in a coil when connected to 12V dV source. If the same coil is connected to a 12V, 50 rad/s a.c. source, a current of 2.4 A flows in the circuit. Determine the ... the coil. Also find the power developed in the circuit if a 2500μF capacitor is connected in series with the coil.

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**Description :** A circular coil, of radius a, (having N turns) is made to rotate about its vertical diameter with an angular speed ω. The coil is present in a region where a uniform horizontal magnetic field B is present. If the coil has a resistance ... a^2 ωB}{\sqrt{2}R}\) and \(\frac{(N\pi a^2 ωB)}{\sqrt{2}R}\)

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**Description :** An air plane, with 20 m total wing span is flying with a speed of 250 m/s, straight south, parallel to the earth’s surface. The earth’s magnetic field has a horizontal component of 2 x 10-5 Wb m-2 and the dip angle is 60° . Calculate the emf induced between the plane tips.

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Find the induced EMF in an inductor of 2mH and the current rate is 2000 units. a) 4 b) -4 c) 1 d) -1

**Description :** Find the induced EMF in an inductor of 2mH and the current rate is 2000 units. a) 4 b) -4 c) 1 d) -1

**Last Answer :** b) -4

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**Description :** A small coil, having n turns each of (everage) radius r, is held normal to the magnetic field liens in the region between the (flat) pole pieces of a horse shoe magnet. The terminals ofthe coil are connected to a ... the magnetic field), is the graph labelled as graph. (1) K (2) L (3) M (4) N

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**Description :** The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. The self inductance of the indicator i

**Last Answer :** The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. The ... B. `0.4` C. `0.1` D. `1.0`

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**Description :** A rectangular loop, and a circular loop, are moving out of a uniform magnetic field region, to a field free region, with a constant velocity V'. In which loop would the induced emf be constant ... age out of field region. (The magnetic field is directed normal to the plane of both the loops).

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**Description :** A conducting circular loop is placed in a uniform magnetic filed (of induction B'tesla), with its plane normal to the field. If the radius of the loop were to start shrinking at a constant rate dr/dt. The induced emf, at the instant ... {dr}{dt})B\) (4) \(-\frac{1}{2}\pi r^2 B(\frac{dr}{dt})B\)

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**Description :** An electrical circuit is made up of an inductance (L), a capacitor (C) and a resistor (R), connected in series. When it is connected across the mains (Voltage = 111.8 V ≃ 12500 V), it draws 125W power from these mains. ... , 142Ω (2) 106.5Ω , 213Ω , 106.5Ω (3) 89Ω , 178Ω , 89Ω (4) 71Ω , 142Ω , 71Ω

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**Description :** A mini generator has a coil of 1000 turns, each of area 10-2m2 . The coil is placed with its plane perpendicular to a uniform magnetic field of intensity 25 mT and is rotated at a uniform rate of 100 rotations per ... 3) 100 volt, 0 volt, 100 volt, 0 volt (4) 100 volt, 100 volt, 100 volt, 100 volt

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**Description :** A sinusoidal A.C. voltage source, of adjustable frequency, is connected across a series LCR' combination. The inductance (L) and the capacitance (C), present in the circuit, can be expresssed in terms of the quality factor (Q) the ... \(L=\frac{1}{ω_0Q^2R^2}\) and \(C = (\frac{Q^2R^2}{ω_0})\)

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**Description :** A given series LCR circuits is connected across a simusoidal AC voltage source. v = v0 sin (ωt) The inductance, L, in the circuit, has a value equal to 1/ω2C. The rms voltage drop, across L, C, and R, of this circuit, are ... {2}}\) (4) \(\frac{v_0}{\sqrt{2}R}.\frac{1}{ωC};\frac{v_0}{R}\) and v1

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**Description :** The magnetic flux ϕ , through a stationary loop of wire, having a resistance R, varies with time as ϕ = (at2 + bt) where a and b are positive constants. The average emf, and the total charge flowing in the loop in the time interval t ... b \tau}{R})\) (4) \(2(a\tau +b),(\frac{a\tau ^2+b \tau}{2R})\)

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**Description :** The emf induced in a coil is 1 volt when current in it changes from 0 to 100 mA in time 10mS. Its inductance (in mH) value is A) 10 B) 50 C) 100 D) 1000

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**Description :** A small square loop of wire, of side l, is placed inside a large square loop of wire of side L (L >> l). The loops are coplanar and their centres coincide. The mutual inductance of the system is proportional to (1) \(\frac{l}{L}\) (2) \(\frac{l^2}{L}\) (3) \(\frac{l}{L}\) (4) \(\frac{L^2}{l}\)

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**Description :** It is required to improve the sharpness of resonance of a series LCR circuit by a factor of 4. This requirement can be met by (1) increasing the resistance to 4 times its present value; leaving L and ... C and R unchanged (4) decreasing the capacitance by a factor or 4; leaving L and R unchanged

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**Description :** A horizontal metal frame, ABCD, moves with a uniform (horizontal) velocity of 0.2 m/s, into a uniform field of 10-2T, acting vertically downwards. AB = 0.1m and AD = 0.2m and the ... current, the force required to move the frame with a constant velocity, and the power spend by the external agency

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**Description :** A conducting rod of length L lies along the y-axis with one end at origin and the other end at (0, L, 0). There is a magnetic field B = B0y\(\hat{k}\) in that region. If the rod moves with a velocity V = V0\(\hat ... {B_0V_0L}{2}\) (2) \(\frac{B_0V_0L^2}{2}\) (3) B0V0 Ld (4) \(\frac{B_0V_0L^2}{4}\)

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**Description :** A small circular loop, of radius 3cm, and a bigger loop, of radius 20cm, are placed coaxially, at a distance of 15cm as shown in the figure. A current of 2A flows through the smaller loop. Find the flux linked with the bigger loop and the mutual inductance of the two loops.

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**Description :** An LCR series circuit, with resistance 100Ω is connected to an a.c. source of 200 V and angular frequency 300 rad/s. When the capacitance is removed from the circuit, current lags behind the ... removed from the circuit, the current leads the voltage by 600 . Calculate the current in the circuit.

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**Description :** The phenomenon of producing emf in the coil due to change of current in the coil itself is called: a. mutual induction b. self-induction c. self-inductance d. mutual inductance

**Last Answer :** d. mutual inductance

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**Description :** An a.c. source of frequency 50 Hz is applied to a series circuit of resistance 20Ω , an inductance of 100 mH and a capacitance of 30μF . Does the current lag or lead the applied voltage? If so, by what (phase) angle?

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**Description :** Two coils m and n having 10 turns and 15 turns respectively are placed close to each other. When 2A current is passing through coil m, then flux linked with coil n is 1.8 x 10-4 wb per turn. If 3A current passed through coil n, then calculate the flux linked per turn of coil m.

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