Title 5-electromagnetic-induction-.pdf ✅

Electromagnetic Induction 1. A square of side L meters lies in the x − y plane in a region, where the magnetic field is given by B = B0(2iˆ + 3jˆ + 4kˆ )T, where B0 is constant. The magnitude of flux passing through the square is : (A) 2B0L 2Wb (B) 3B0L 2Wb (C) 4B0L 2Wb (D) √29B0L 2Wb 2. 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 emf induced across the ends of the rod is : (A) 2Bωl 3 2 (B) 3Bωl 3 2 (C) 4Bωl 2 2 (D) 5Bωl 2 2 3. A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction B, constant in time and space, pointing perpendicular to and into the plane of loop exists everywhere. The current induced in the loop is : (A) BLv/R clockwise (B) BLv/R anticlockwise (C) 2BLv/R anticlockwise (D) zero 4. A rectangular loop of size (2m × 1m) is placed in x − y plane. A uniform but time varying magnetic field of strength B⃗ = (20tiˆ + 10t 2 jˆ + 50kˆ )T where t is time elapsed in second. The magnitude of induced emf (in V ) at time t is : (A) 20 + 20t (B) 20 (C) 20t (D) Zero 5. 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? (A) The current will reverse its direction as the electron goes past the coil (B) No current induced (C) abcd (D) adcb 6. A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B⃗ . At the position MNQ the speed of the ring is v and the potential difference developed across the ring is :
(A) Zero (B) BvπR 2 /2 and M is at higher potential (C) 2BRv and Q is at higher potential (D) πBRv and Q is at higher potential electron 7. An ideal inductor of 10H is connected in series with a resistance of 5Ω and a battery of 5 V. 2 s after the connection is made, the current flowing (in ampere) in the circuit is : (A) (1 − e) (B) e (C) e −1 (D) (1 − e −1 ) 8. A circular coil expands radially in region of magnetic field and no electromotive force is produced in the coil. This can be because (A) The magnetic field is constant (B) The magnetic field is in the same plane as the circular coil and it may or may not vary (C) The magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably (D) There is a constant magnetic field in the perpendicular (to the plane of the coil) direction 9. A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement(s) from the following. (A) The entire rod is at the same electric potential (B) There is an electric field in the rod (C) The electric potential is highest at the centre of the rod and decrease towards its ends (D) The electric potential is lowest at the centre of the rod and increase towards its ends 10. The mutual inductance M12 of coil 1 with respect to coil 2 (A) Increases when they are brought nearer (B) Depends on the current passing through the coils (C) Increases when 1 of them is rotate about an axis (D) Is the same as M21 of coil 2 with respect to coil 1 11. The current (I) in the inductance is varying with time according to the plot shown in figure. Which one of the following the correct variation of voltage with time in the coil ? (A) (B) (C) (D) 12. A choke coil should have : (A) High inductance and high resistance (B) Low inductance and low resistance
(C) High inductance and low resistance (D) Low inductance and high resistance 13. A thin flexible wire of length L is connected to two adjacent fixed point and the carries a current I in the clockwise direction, as shown in the figure. When the system is put in a uniform magnetic field of strength B going into the plane of the paper, the wire takes the shape of the circle. The tension in the wire is : (A) IBL (B) IBL π (C) IBL 2π (D) IBL 4π 14. The current i in a coil varies with time as shown in the figure. The variation of induced emf with time would be : (A) (B) (c) (D) 15. In an LR circuit current at t = 0 is 20 A. After 2s it reduces to 18 A. The time constant of the circuit is : (in second) (A) ln ( 10 9 ) (B) 2 (C) 2 ln ( 10 9 ) (D) 2ln ( 10 9 ) (C) 16. Dimensions of magnetic flux electric flux are : (A) [LT −1 ] (B) [TL −1 ] (C) [L 3T 2A −2 ] (D) [M0L 0T 0 ] 17. The ratio of time constants during current growth and current decay of the circuit shown in figure is :
(A) 1: 1 (B) 3: 2 (C) 2: 3 (D) 1: 3 18. The self inductance L of a solenoid of length l and area of cross section A, with a fixed number of turns N increases as : (A) l and A increase (B) l decreases and A increases (C) l increases and A decreases (D) both l and A decreases 19. A cylindrical space of radius R is filled with a uniform magnetic induction B parallel to the axis of the cylinder. If B changes at a constant rate, the graph showing the variation of induced electric filed with distance r from the axis of cylinder is : (A) (B) (C) (D) 20. A metal plate is getting heated. It can be because (A) A direct current is passing through the plate (B) It is placed in a time varying magnetic field (C) It is placed in a space varying magnetic field, but does not vary with time (D) A current (either direct or alternating) is passing through the plate 21. Assertion : The SI unit of T−m2 s is equivalent to volts. Reason : Both are the unit of potential difference. (A) A (B) B (C) C (D) D (E) E 22. Assertion : When number of turns in a coil is doubled, coefficient of self-inductance of the coil become 4 times. Reason : This is because L ∝ N 2 . (A) A (B) B (C) C (D) D (E) E 23. An e.m.f. is produced in a coil, which is not connected to an external voltage source. This can be due to : (A) The coil being in a time varying magnetic field (B) The coil moving in time varying magnetic field (C) The coil moving in a constant magnetic field (D) The coil is stationary in external spatially