CHAPTER 27 CURRENT IN A MAGNETIC FIELD CHAPTER 27 EXERCISE 27A
1. A straight wire of length 0.8 m, carrying a current of 10 A, lies perpendicular to a uniform magnetic fi eld. It experiences a force of 0.2 N. Calculate the magnetic fl ux density B.
2. Determine the force produced on a straight wire, 1.1 m in length, which carries a current of 1.2 A in a magnetic fi eld of fl ux density 200 mT, which is perpendicular to the wire.
3. Determine the direction of force on each of the conducting wires (i)–(iv).
I (i) I I B (iii) FIG. 27.10 H
4. Calculate the force on each section of the wire given below, if B = 3 T and the current fl owing through the wire is 10 A.
60° I a 10 cm FIG. 27.11 b c d 8 cm e B (iv) H FIG. 27.12
6. A square coil of wire of side 15 cm, carrying a 12 A current was placed in a uniform magnetic fi eld of fl ux density 2 T. Calculate the force acting on each side of the coil when the plane of the coil is parallel to the magnetic fi eld. In each case, convert the forces to moments about the axis assuming the coil is pivoted and rotates along its axis of symmetry.
7. A straight conductor of length 50 m has a current of 13 A fl owing through it and is placed in a magnetic fi eld of fl ux density 5 T. Calculate the force exerted on the conductor if it is placed at 25° to the magnetic fi eld. Determine also in which direction the force acts.
I I (ii) c S
5. A rectangular coil of wire is placed in a uniform magnetic fi eld as shown in Fig. 27.12. Determine the direction of force on each side of the coil: a, b and c.
