Question

1) [7 marks] A long straight wire hangs vertically through the middle of a metal basketball hoop of radius R = 23.0 cm. The hoop is horizontal. The wire carries a current of I = 1.56 A, moving vertically upward from the ground toward the sky. a) Sketch the magnetic field inside the hoop, as viewed from above it. b) What is the magnitude of the magnetic field at the hoop's location? c) Is there a net magnetic flux through the hoop? 2) [9 marks] A bullet is made of magnetic iron. It is fired through the central axis of a N = 65-turn solenoid which is a cylinder with radius r = 2.50 cm and l = 15.8 cm long. The bullet's speed is v = 301 m/s. Assume B is orieinted along the direction of the bullet's motion, so that PB = BA. a) What is the cross-sectional area of the solenoid? b) What is its inductance? c) How long will the bullet take to pass through the solenoid? d) If an EMF of 5.00 mV is induced while the bullet passes through the solenoid, what magnitude of B does the bullet carry? 3) (8 marks) Two concentric circular wires lie flat in the ry-plane. They share a common origin. The outer wire has R1 = 10.0 m and the inner wire has R2 = 9.00 m. Both wires have a current of I = 3.00 A passing through them, moving counter-clockwise. a) What is the strength and direction of the B-field at the center of the circles? b) Is the force between wires attractive or replulsive? c) Will the wires move? 4) [6 marks] Some children are playing with a Slinky, which is 42.0 cm long, has 500 turns per metre of wire in it, and a diameter of 9.00 cm. They place it on top of their grandfather's record player, and set it to the maximum rotation rate of 78.0 RPM. Given the Earth's magnetic field strength of about 0.0560 mT, what maximum EMF could be induced in the Slinky, assuming ideal contrived) geometries? 5) (10 marks) A diamond-shaped kite keeps its shape because of two supports: a horizontal spar, and a vertical spine. Suppose you are flying a kite with a metal conducting spar of length l = 1.20 m. The spine is made of wood. Where you are located, B = (-5.78 x 10-)k T (you must be near the Geomagnetic South Pole!). You run horizontally with your kite with a speed of v = 4.15 m/s, in the +j direction. a) As viewed from above, will electrons on the spar tend to move to the left or right end of the spar? Why? b) Using E = Blu, what maximum potential difference could exist across the spar? c) Using E= AV/L, what electric field strength could exist on the spar? d) Now suppose that instead of the spar, the spine is the metallic support, and it's 1.60 m long, and it makes an angle of 75.0° with respect to the ground. As you run along +j, are electrons affected at all?

Answer 1

11.56A ma roho tild - llo I 410X10 1.56 20 - 2x 0:23. = 42.6 T. Å are (e) No, since. & and perpendiculare 20. STOP 2.50cm 65 7wns 15.8cm 100 (q) cross sectional Area - A = 1.9625 103 m b) gonductance - 4x107x65** 15.8 x 13425 100 X10 MEN -65 = 411.+ = 65.315 IS

© time = 15.8x10 to pass 301 - 0.059 sec emf induced =10 At. 58103. _ - A AB O AB = At. 5% 10 x 0. 052 1.9625 X 1003 FAB. = 0.132] Bi - Baada Ballet will carry 0.132 T:

2T RI = 4 x X10-7x31 +!] 20 10 g E to 267x1077 3. Force will be attractive. since current in both wire i in same direction. @ No, as Med Rebou Force will. be in all the direction so, Net Force will be zero.