Unformatted text preview: the current that one needs to circulate through the wire in order to have no tension in the supporting leads g = 9:8m=s2? Ignore all magnetic e ects on the exible leads A 0:07A; ! Battery B 1:59A; ! C 1:59A; D 0:49A; ! correct E 0:49A; 1m 14. The gure shows the path of an electron that passes through three regions containing uniform magnetic elds of magnitudes B1 , B2 and B3. Which of the following statements is correct, A cannot deduce it from the gure alone B1 B B1 B2 B3 correct C B3 B2 B1 B2 D B2 B1 B3 E B1 = B2 = B3
B3 7 15. A particle of charge +2C moves along a magnetic eld B = 0:03T i , 0:15T j with velocity v = 2 106m=si + 3 106m=sj. The force on the particle is, A ,7:8 105N k correct B ,6:2 105N i C ,4:2 105N j D 4:2 105N k E 6:2 106N k 16. A metal wire of mass m slides freely on two horizontal rails, spaced a distance d apart, as shown in the gure. The tracks are connected to a battery that supplies a constant current i through the circuit formed by the rails and the moving wire. There is an externally applied uniform vertical magnetic eld B pointing upwards out of the paper. The switch is closed at t = 0, when the wire is at rest. The speed and direction of the wire's motion at time t are, A iBdt2=2m, left i S B iBdt=m, right C iBdt=m, left correct Magnetic D iB=dm, left i Field 2 d E iBdt =2m, right
Rails Freely movable wire i 8 17. A uniform magnetic eld is directed into the page. A charged particle, moving in the plane of the page, follows a counter-clockwise spiral of increasing radius as shown. A reasonable explanation is, A the charge is positive and slowing down B the charge is negative and slowing down C the charge is positive and speeding up correct D the charge is negative and speeding up E this cannot happen correct 18. A particle of charge 20C enters a 50m long `region of cr...
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