Unformatted text preview: ossed electric and magnetic elds with velocity 200m=s. The electric eld, of 20V=m, is vertical. The magnetic eld is perpendicular to the page. What is the direction and intensity of the magnetic eld that is needed for the particle to follow a straight trajectory? A 4T , into the paper B 4T , out of the paper B perpendicular C 0:1T , into the paper correct + to page D 0:1T , out of the paper E 10T , into the paper
v=200m/s 50 m 9 19. Two ions a and b, of equal mass and of equal magnitude of their charges are found travelling around circular orbits in the same uniform magnetic eld, as shown in the gure. The eld is into the page of the diagram. b travels clockwise and a travels counterclockwise. Which of the following statements is true? A The speed of a is equal to the speed of b. a is positively charged and b is negatively charged. B The speed of a is larger than that of b, a is positively charged and b is negatively charged. C The speed of a is smaller than that of b, a is positively charged and b is negatively charged. correct D The speed of a is smaller than that of b, a is negatively charged and b is positively charged. E a is positively charged and b is negatively charged but cannot decide the relative speeds from the information given. b a B 10 20. The gure shows a rectangular, 20 turn coil of wire, 10cm by 5cm. It carries a current of 100mA and is hinged along one side. It is mounted in the xy plane, at an angle of 30 degrees to the direction of a uniform magnetic eld of 0:5T . The magnitude of the torque vector acting on the coil about the hinge line is, A 8:6 10,3N m B 5 10,3N m y C 4:3 10,3N m correct ,2 N m D 8:6 10 E 2:5 10,3N m
Hinge line x 30 B z o 11...
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