Tiêu đề 06. ELECTROMAGNETIC INDUCTION.pdf ✅

06. ELECTROMAGNETIC INDUCTION NEET PREPARATION (MEDIUM PHYSICS PAPER) Date: March 12, 2025 Dura on: 1:00:00 Total Marks: 180 INSTRUCTIONS INSTRUCTIONS PHYSICS 1. A conducting loop being pulled out of magnetic field with a speed . Which of the following plots may represent the power delivered by the pulling agent as a function of the speed ? (1) (2) (3) (4) 2. The current in a circuit builds up to of its steady state value in . The time constant of this circuit is (1) (2) (3) (4) 3. Statement A : An emf can be induced by moving a conductor into a magnetic field. Statement B : An emf can be induced by changing the mag‐ netic field. (1) Statement A is correct but Statement B is incorrect. (2) Statement A is in- correct but Statement B is correct. (3) Both statements are correct. (4) Both Statements are incorrect. 4. A jet plane having a wing - span of is trav‐ eling horizontally towards east with a speed of . If the Earth's magnetic field at the location is and the angle of dip is , then the potential difference between the ends of the wing is (1) (2) (3) (4) 5. Magnetic flux (in weber) in a closed circuit of resistance varies with time as . The magnitude of induced current at is (1) (2) (3) (4) 6. A circuit contains two inductors of selfinduc‐ tance and in series. If is the mutual in‐ ductance then the effective inductance of the cir‐ cuit shown will be (1) (2) (3) (4) 7. In the figure, a conducting ring of certain resis‐ tance is falling towards a current carrying straight long conductor. The ring and conductor are in the same plane. Then the (1) induced electric current is zero (2) induced electric current is anticlockwise v v a b c d LR th 3 4 4 s s 4 In 2 s 3 In 3 s 2 In 2 s 1 In 2 25 m 3600 km/hour 4 × 10 −4 T 30 ∘ 4 V 5 V 2 V 2.5 V φ 10 Ω t(sec) φ = 6t 2 − 5t + 1 t = 0.25 s 0.2 A 0.6 A 1.2 A 0.8 A L1 L2 M L1 + L2 L1 + L2 − 2M L1 + L2 + M L1 + L2 + 2M
(3) induced electric current is clockwise (4) ring will come to rest 8. An of is induced in a metal rod of length held normal to a uniform magnetic field of , when moves with a velocity of (1) (2) (3) (4) 9. When a sheet of metal is placed in a magnetic field, which changes from zero to a maximum value, the induced currents are set up in the di‐ rection shown in figure. What is the direction of magnetic field? (1) West to East (2) Out of the plane of the paper (3) South to North (4) Into the plane of the paper 10. The back e.m.f. induced in a coil, when current changes from 1 ampere to zero in one millisec‐ ond, is 4 volts, the self-inductance of the coil is (1) (2) (3) (4) 11. Two coils have mutual inductance . The current changes in the first coil according to equation , where and . The maximum value of emf in volt in the second coil is: (1) (2) (3) (4) 12. Assertion : The possibility of an electric bulb fusing is higher at the time switching ON and OFF. Reason : Inductive effects produces a surge at the time of switch OFF and switch ON (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 13. An average induced e.m.f. of appears in a coil when the current in it is changed from in one direction to in opposite direction in . Self-inductance of the coil is (1) (2) (3) (4) 14. A metal conductor of length rotates verti‐ cally about one of its ends at an angular velocity of . If the horizontal component of earth's magnetic field is , then the developed between the two ends of conductor. (1) (2) (3) (4) 15. A generator has an of and in‐ ternal resistance of . Its terminals are connected to a load of . The voltage across the load is (1) (2) (3) (4) 16. A coil is placed in magnetic field such that plane of coil is perpendicular to the direction of magnetic field. The magnetic flux through a coil can be changed (A) By changing the magnitude of the magnetic field within the coil. (B) By changing the area of coil within the mag‐ netic field. (C) By changing the angle between the direction of magnetic field and the plane of the coil. (D) By reversing the magnetic field direction abruptly without changing its magnitude. (1) and only (2) and only (3) and only (4) and only 17. An average induced e.m.f of appears in a coil when the current in it is changed from in one direction to in opposite direction in . Self- inductance of the coil is: (1) (2) (3) (4) 18. Statement A : The back emf in a dc motor is maximum when the motor has just been switched on. Statement B : When motor is switched on, it has maximum speed. (1) Statement A is correct but Statement B is incorrect. (2) Statement A is in- correct but Statement B is correct. (3) Both statements are correct. (4) Both Statements are incorrect. emf 0.08 V 10 cm 0.4T 3.2 ms −1 2 ms −1 0.5 ms −1 20 ms −1 4 × 10 −3H 10 −3H 4H 1H 0.001H I = I0 cos ωt I0 = 20 A ω = 100π rad s −1 12π 8π 2π 6π 1 V 10 A 10A 0.5 sec 25 mH 75 mH 100 mH 50 mH 2 m 50 rad/ sec 0.5 T EMF 5 V 50 V 15 V Zero e. m. f. 440 volt 4000 hm 4000 ohm 220 volt 440 volt 200 volt 400 volt A C A, B C A, B D A B 1 V 10 A 10 A 0.5 sec 25 mH 50 mH 75 mH 100 mH
19. A solenoid of inductance carries a current of . What is the magnetic energy stored in the solenoid? (1) (2) (3) (4) 20. Statement A : The presence of large magnetic flux through a coil produces current in the coil. Statement B : Magnetic flux is essential to maintain an induced current in the coil. (1) Statement A is correct but Statement B is incorrect. (2) Statement A is in- correct but Statement B is correct. (3) Both statements are correct. (4) Both Statements are incorrect. 21. The flux linked with a ring at any time ' ' is given by , the induced at is: (1) (2) (3) (4) 22. A jet plane of wing span is traveling to‐ wards west at a speed of . If the earth's total magnetic field is and the dip angle is , at that place, the voltage differ‐ ence developed across the ends of the wing is (1) (2) (3) (4) 23. Statement A : The self-inductance of a long solenoid is in‐ versely proportional to the area of cross-section. Statement B : Self inductance of a solenoid depends on total number of turns in it. (1) Statement A is correct but Statement B is incorrect. (2) Statement A is in- correct but Statement B is correct. (3) Both statements are correct. (4) Both Statements are incorrect. 24. A straight conductor of length moves at a speed of , perpendicular to the magnetic field of induction of , then induced emf is (1) (2) (3) (4) 25. A rectangular coil is held horizontally and a magnet is allowed to fall vertically through it. The acceleration of the magnet while passing through the coil is : (1) equal to (2) less than (3) more than (4) sometimes less and sometimes more than 26. The flux associated with coil changes from 1.35 to within . Then, the charge flows through the coil, if resistance of coil is is: (1) (2) (3) (4) 27. The current following through an inductance coil of self inductance at different time in‐ stants is as shown. The emf induced between and is nearly (1) (2) (3) (4) 28. A conducting circular loop is placed in a uni‐ form magnetic field, with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of . The induced emf when the radius is , is (1) (2) (3) (4) 29. If in a coil rate of change of area is mil‐ lisecond and current becomes from 2 in . If magnitude of field is 1 tesla then self-inductance of the coil is (1) (2) (3) (4) 30. A 10 metre wire kept in east-west falling with velocity perpendicular to the field . The induced e.m.f. across the terminal will be (1) (2) (3) (4) 31. Assertion : Acceleration of a magnet falling through a long solenoid (or copper ring) decreases. Reason : The induced current produced in a circuit always 2 H 1 A 4 J 2 J 5 J 1 J t φ = 5t 2 − 30t + 150 Emf t = 2 sec 10 V −10 V 25 V −25 V 20 m 400 m s −1 4 × 10 −4 T 30 ∘ 3.2 V 6.4 V 1.6 V 0.8 V 4 m 10 ms −1 0.1 Wb/m2 8 V 4 V 1 V 2 V g g g g Wb 0.79 Wb s 1 10 7Ω 0.08 C 0.8 C 0.008 C 8 C 6 mH t = 20 s t = 40 s 2 × 10 −2 V 3 × 10 −4 V 4 × 10 −3 V 30 × 10 2 V B = 0.025T 1 mms −1 2 cm 2πμV πμV μV π 2 2μV 5 m2/s 1 amp amp 2 × 10 −3 sec 5 H 2 H 10 H 20 H 5 m/ sec 0.3 × 10 −4 Wb/m2 1.5 mV 0.15 mV 15.0 mV 150 mV