Master WS 6 A Physics XIIth Electromagnetic Induction.pdf

Corporate Office : Aakash Tower, 8, Pusa Road, New Delhi-110005, Ph.011-47623456 Worksheet for School/Board Exam Preparation_2024-25 MM : 30 Master Worksheet–6(A) Time : 90 min....

Corporate Office : Aakash Tower, 8, Pusa Road, New Delhi-110005, Ph.011-47623456 Worksheet for School/Board Exam Preparation_2024-25 MM : 30 Master Worksheet–6(A) Time : 90 min. Class-XII Topics covered : Physics : Electromagnetic Induction PHYSICS General Instructions: (i) All questions are compulsory. (ii) The question paper has four sections and 16 questions (iii) Section-A has 5 multiple choice questions of 1 mark each. (iv) Section-B has 5 questions of 1 mark each comprising very short answer type questions, true & false type questions and fill in the blanks or assertion-reason type questions. (v) Section-C has 3 short answer type questions of 2 marks each and 1 short answer type question having 4 marks. (vi) Section-D has 1 long answer type question of 5 marks with internal choice and 1 case study-based question of 5 marks. (vii) There is no overall choice. However, internal choice has been provided in long answer type question. A student has to attempt only one of the alternatives in such a question. (viii) Wherever necessary, neat and properly labelled diagrams should be drawn. SECTION-A Multiple Choice Questions: Q1. A rectangle of side length L and breadth b lies in the x-y plane. Magnetic field in the space given  by = ( ) B B0 2iˆ + 3 jˆ + 4kˆ T where B0 is constant. The magnitude of magnetic flux (in Wb) passing through the rectangle is (L and b are in meter) (1) 4 B0Lb (2) B0Lb (3) 2 B0Lb (4) Zero Q2. The inductance of a closed packed coil of 400 turns is 8 mH. A current of 5 mA is passed through it. The magnetic flux per turn is (µ0 = Permeability of free space)  1   1  (1)  µ0  Wb (2)  µ0  Wb  4 π   2 π   1  (3)  µ0  Wb (4) (0.4μ0) Wb  3π  (1) Master Worksheet-06(A)_Physics-XII Worksheet for School/Board Exam Preparation_2024-25 Q3. The energy stored (in joule) in an inductor of inductance L henry when it carries a current I ampere is (1) LI (2) LI2 1 2 (3) LI (4) L2I2 2 Q4. Two concentric rings of different size lie in the same plane. The current in the inner loop is clockwise and increases with time. The current in the outer loop is (1) Anti clockwise (2) Clockwise (3) Zero (4) First anticlockwise then clockwise Q5. If magnetic flux as a function of time t is given by, φ = t2 + 2t + 1, where φ is in weber and t in second, then magnitude of average induced emf during t = 0 to 3 second will be (1) 4 volt (2) 1 volt (3) 5 volt (4) 2 volt SECTION-B Short Answer Type Questions: Q6. What is the dimensional formula for mutual inductance?   Q7. Write the formula of magnetic flux in terms of magnetic field vector B and area vector A. Q8. State Lenz’s law True/False Type Questions: Q9. Time varying magnetic field can not induce emf. Fill in the blanks: Q10. The magnitude of the induced emf in a circuit is equal to the time rate of change of ____ through the circuit. SECTION-C Short Answer Type Questions: Q11. Discuss the various methods of producing emfs by electromagnetic induction. Q12. How is mutual inductance of coils affected when (i) separation between the coils is increased? (ii) number of turns of each coils is increased? Explain your answer. Q13. Two inductors having inductances L1 and L2 are connected (i) in series, (ii) in parallel. What is their equivalent? Three inductors of 2 H each are connected as shown. What will be the equivalent inductance of the given network? Q14. Define self inductance. Write the SI unit. Find an expression for the self inductance of a long solenoid. Give two factors on which self inductance of an air-cored long solenoid depends. (2) Worksheet for School/Board Exam Preparation_2024-25 Master Worksheet-06(A)_Physics-XII SECTION-D Long Answer Type Question: Q15. Radius of a circular coil is given by R = R0 (1 + αt). If a constant magnetic field B0 exists perpendicular to the coil (where α is a positive constant) (i) Find the emf induced in the coil as a function of time. (ii) If the resistance of the circular coil is r, find the charge flown in the coil during the time interval from t = 0 s to t = 2 s. OR Describe with neat and suitable diagram, the construction and working of AC generator. Derive the expression of the emf induced. CASE STUDY BASED: Q16. In year 1820 Oersted discovered the magnetic effect of current. Faraday gave the thought that reverse of this phenomenon is also possible i.e., current can also be produced by magnetic field. Faraday showed that when we move a magnet towards the coil which is connected by a sensitive galvanometer, the galvanometer gives instantaneous deflection showing that there is an electric current in the loop. Whenever relative motion between coil and magnet takes place an emf induced in coil. If coil is in closed circuit then current is also induced in the circuit. This phenomenon is called electromagnetic induction. Based on the above paragraph, answer the following questions: (i) Two similar circular loops carry equal currents in the same direction. On moving the loops further apart, the electric current will (1) Remain unaltered (2) Increases in one and decreases in the second (3) Increase in both (4) Decrease in both (ii) Which of the following statements is correct? (1) The induced emf is not in the direction opposing the change in magnetic flux. (2) The relative motion between the coil and magnet produces change in magnetic flux. (3) Emf is induced only if the magnet is moved towards coil. (4) Emf is induced only if the coil is moved towards magnet (iii) Whenever there is a relative motion between a coil and a magnet, the magnitude of induced emf set up in the coil does not depend upon the (1) Relative speed between the coil and magnet (2) Magnetic moment of the coil (3) Resistance of the coil (4) Number of turns in the coil (3) Master Worksheet-06(A)_Physics-XII Worksheet for School/Board Exam Preparation_2024-25 (iv) A coil of metal wire is kept stationary in a non-uniform magnetic field (1) An emf and current both are induced in the coil (2) A current is induced but no emf is induced in the coil (3) An emf is induced but no current is induced in the coil (4) Neither emf nor current is induced in the coil (v) The dimensional formula for induced emf is (1) [ML2 T−3 A−1] (2) [ML2 T−1 A] (3) [ML2 A] (4) [MLT−2 A−2]    (4)