chapter: magnetism

(a) 300 FIGURE 3(a) A metal rod of length 0. 15 m which carries a current of 6.0 A is placed in a uniform magnetic field, B = 0.28 T as shown in FIGURE 3(a). (i) What is the magnetic force on the rod? [5 marks] (ii) One application of a magnetic force acting on a current-carrying wire in a magnetic field is the operating principle of most speakers in sound systems. Explain briefly how it works. [3 marks] (b) ion Plate S X B X FIGURE 3(b) An ion of charge, q = +1.60 x 10-19 C entering a uniform magnetic field, B = 0.3 T with a velocity, v = 6.5 x 105 m s" as shown in FIGURE 3(b). The mass of the ion is 1.76 x 10-27 kg. (i) Copy FIGURE 3(b). Sketch the path of the ion in the magnetic field. [1 mark] (ii) Calculate the distance from the hole that the ion strikes the plate. [6 marks] (iii) Another ion of twice the mass but has the same charge and velocity enters the magnetic field. Show on the same figure in (i) above, the path of this ion. [2 marks] (a) FIGURE 4(a) A square coil RSTU of sides 5.0 cm carrying a current, I of 2.5 A is placed in a uniform magnetic field, B of 2.4 T as shown in FIGURE 4(a). i) Determine the direction of the magnetic force on each side of the square. [2 marks] ii) Calculate the torque on the coil. [5 marks] (iii) State one application of the torque on the coil. [1 mark] (b) 1.8 A 12 cm 3.5 A FIGURE 4(b) Two long parallel wires, 12.0 cm apart are carrying current 1.8 A and 3.5 A respectively in the same directions as shown in FIGURE 4(b). (i) Calculate the magnetic force per unit length experienced by both wires. [4 marks] (ii) Is the force attractive or repulsive? [1 mark] (iii) The magnetic field at the midpoint between both wires is 5.0 x 10* T out of the page. If a proton moves with a velocity of 2.8 x 105 m s" at the midpoint between the wires, determine the magnetic force acting on the proton. [5 marks] END OF QUESTION PAPER