Physics-DPP-4-Magnetism

PHYSICS Topic: Magnetism Date: 1. AB and CD are smooth, parallel, horizontal rails on which a conductor T can slide. A cell, E, drives current i through the rails and T. (a) The current in the rails will set up a magnetic field over T. (b) T will experience a force to the right. (c) T will experience a force to the left. (d) T will not experience any force. 2. In the pervious questions, (a) the force on T is proportional to i. (b) the force on T is proportional to i2. (c) if the direction of i is reversed in the circuit by reversing E, the force on T will reverse in direction. (d) if the direction of i is reversed in the circuit by reversing E, the force on T will remain in the same direction. 3. Two long, thin, parallel conductors, separated by a distance d, carry current i1 and i2. The force acting on unit length of any one conductor is F. (a) F is attractive, if i1 and i2 flow in the same direction. (b) F is attractive, if i1 and i2 flow in opposite directions. (c) F is the same for both conductors. (d) F is different for the two conductors. 4. In the previous question, (a) F  (i i ) (b) F  (i i )2 (c) F µ 1 (d) F µ 1 1 2 1 2 d 2 d 5. AB and CD are smooth parallel rails, separated by a distance l, and inclined to the horizontal at an angle . A uniform magnetic field of magnitude B, directed vertically upwards, exists in the region. EF is a conductor of mass m, carrying a current i. For EF to be in equilibrium, (a) i must flow from E to F (b) Bil = mg tan  (c) Bil = mg sin  (d) Bil = mg PHYSICS Topic: Magnetism Date: 6. In the previous question, if B is normal to the plane of the rails, (a) Bil = mg tan  (b) Bil = mg sin  (c) Bil = mg cos  (d) equilibrium cannot be reached r ur r ur 7. A flat coil carrying a current has a magnetic moment μ . It is placed in a magnetic field B such that μ is antiparallel to B . The coil is (a) Not in equilibrium (b) in stable equilibrium (c) in unstable equilibrium (d) in neutral equilibrium ur uuur r r 8. A conductor AB carries a current i in a magnetic field B . If AB = r and the force on the conductor is F r r r ur (a) F does not depend on the shape of AB (b) F = i (r ´ B) r ur r r r ur (c) F = i(B ´ r) (d) | F |= i( r . B) 9. A semicircular wire of radius r, carrying a current i, is placed in a magnetic field of magnitude B. The force acting on it. (a) Can never be zero (b) Can have the maximum magnitude 2Bir (c) Can have the maximum magnitude Bir (d) Can have the maximum magnitude Bir 10. A flat circular coil, carrying a current, has a magnetic moment . (a)  has only magnitude; it does not have direction. (b) The direction of  is along the normal to the plane of the coil. (c) The direction of  depends on the direction of the current flow. (d) The direction of  does not change if the current in the coil is reversed. PHYSICS Topic: Magnetism Answer Key Date: 1. (a, b) 2. (b, d) 3. (a, c) 4. (a, d) 5. (a, b) 6. (b) 7. (c) 8. (a, b) 9. (b) 10. (b, c)