Tiêu đề MOVING CHARGES AND MAGNETISM.docx.pdf ✅

4.MOVING CHARGES AND MAGNETISM Single Correct Answer Type 1. A particle moving in a magnetic field increases its velocity then its radius of the circle a) Decreases b) Increases c) Remains the same d) Becomes half 2. A wire carrying current I and other carrying 2I in the same direction produces a magnetic field B at the mid point. What will be the field when 2I wire is switched off a) B/2 b) 2B c) B d) 4B 3. Two long parallel copper wires carry currents of 5A each in opposite directions. If the wires are separated by a distance of 0. 5m, then the force between the two wires is a) 10 , attractive −5N b) 10 , repulsive −5N c) 2×10 , attractive −5N d) 2×10 , repulsive −5N 4. An infinitely long straight conductor AB is fixed and a current is passed through it. Another movable straight wire CD of finite length and carrying current is held perpendicular to it and released. Neglect weight of the wire a) The rod CD will move upwards parallel to itself b) The rod CD will move downward parallel to itself c) The rod CD will move upward and turn clockwise at the same time d) The rod CD will move upward and turn anti-clockwise at the same time 5. Two similar coils of radius R are lying concentrically with their planes at right angles to each other. The currents flowing in them are Iand 2I, respectively. The resultant magnetic field induction at the centre will be a) 5μ 0 I 2R b) 3μ 0 I 2R c) μ 0 I 2R d) μ 0 I R 6. A current (i) carrying circular wire of radius R is placed in a magnetic field B perpendicular to its plane. The tension T along the circumference of wire is a) BiR b) 2πBiR c) πBiR d) 2BiR 7. A current of i ampere flows in a circular area of wire which subtends an angle of (3π/2) radian at its centre, whose radius is R. The magnetic induction B at the centre is a) μ 0 i/R b) μ 0 i/2R c) 2μ 0 i/R d) 3μ 0 i/8R Page| 1