Slide 1 / 50 Slide 2 / 50 Magnetism Multiple Choice Practice Problems Slide 3 / 50 Slide 4 / 50 1 A straight wire carries a current down. What is the 2 A loop of wire carries a current in direction of the magnetic field at the point to the counterclockwise direction. What is the direction East from the wire? of the magnetic field inside the loop? A West A Point to the left B East B Points to the right C North C Points out of the page D South D Points into the page E Down E Curls in a clockwise direction Slide 5 / 50 Slide 6 / 50 3 A current carrying wire is placed horizontally and 4 A vertical wire carries a current straight up in a has a current flow to the right. What is the region of the magnetic field directed north. What direction of the magnetic field at point P? is the direction of the magnetic force on the current due to the magnetic field? A Points to the right A East B Points to the left B South C Points to the top of the page C North D Points to the bottom of the page D West E Points out of the page E Applied force is zero
Slide 7 / 50 Slide 8 / 50 5 A horizontal thin wire has a mass m and length L. 6 A horizontal thin wire has a mass m and length L. The wire carries a constant current I. What must The wire carries a constant current I. What must be the direction of the magnetic field in order to be the magnitude of the magnetic field in order to cancel the gravitational force? cancel the gravitational force? A Left A IL/mg B Right B mg/IL C Down the page C Ig/mL D Out of the page D Im/gL E Into the page E Zero Slide 9 / 50 Slide 10 / 50 7 An electron enters a uniform magnetic field 8 A proton enters a uniform magnetic field directed directed in –Z. What is the direction of the in +Z. What is the direction of the magnetic force magnetic force on the electron due to the on the proton due to the magnetic field? magnetic field? A +X direction A +X direction B +Y direction B +Y direction C -X direction C -X direction D –Y direction D –Y direction E Applied force is zero E Applied force is zero Slide 11 / 50 Slide 12 / 50 9 A horizontal wire carries a current to the east. A 10 A circular loop of wire carries a constant current proton moves to the west in the region north from in counterclockwise direction. The loop is placed the current. What is the direction of the magnetic in a uniform magnetic field directed into the page. force on the proton? What is the effect of the magnetic force on the loop? Rotates with respect to A West A its axis B North Rotates with respect to B C East its diameter D South C Contracts its size E Applied force is zero D Expends its size E No effect on the loop
Slide 13 / 50 Slide 14 / 50 11 A proton enters a uniform magnetic field 12 A magnetic field is created by two parallel perpendicular to the field lines. What is the new currents flowing in opposite directions. At which path of the proton as it passes the field? location the magnetic field is greatest in magnitude? A A A A B B B B C C C C D D D D E E E E Slide 15 / 50 Slide 16 / 50 13 Two parallel wires carry currents in opposite 14 Two parallel wires carry currents in the same directions. What is the direction on the net direction. What is the direction of the magnetic magnetic field at point P? force on current I 2 due to current I 1 ? A Left A Left B Right B Right C Top the page C Top the page D Bottom the page D Bottom the page E Into the page E Out of the page Slide 17 / 50 Slide 18 / 50 15 Two parallel wires carry currents in opposite 16 An electron enters a uniform electric field directions. What is the direction of the magnetic perpendicular to the field lines. What must be the force on current I 1 due to current I 2 ? direction of the magnetic field in order to cancel the electric force effect? A Left A Left B Right B Right C Top the page C Top of the page D Bottom the page D Into the page E Out of the page E Out of the page
Slide 19 / 50 Slide 20 / 50 17 An electron enters a uniform electric field 18 What is the magnitude of the magnetic field at perpendicular to the field lines. What is the point B produced by a current I if the magnitude of magnitude of the magnetic field if the electric effect the field at point A is B 0 ? completely canceled? B 0 A Ev A B 2B 0 B v/E C 4B 0 C zero D B 0 /2 D E/v E B 0 /4 E eEv Slide 21 / 50 Slide 22 / 50 19 Two parallel wires carry currents I 1 and I 2 in the 20 An electron with a mass m and charge e enters at same direction and separated by a distance d. The a constant speed v a uniform magnetic field B. magnitude of the magnetic force between the wires What is the radius of the curvature of the electron is F 0 . What is the force between the wires if each in the field? current is doubled and the separation is quadrupled? A mv/eB A 2F 0 B eB/mv B 4F 0 C me/vB C F 0 D mB/ev D F 0 /2 E zero E F 0 /4 Slide 23 / 50 Slide 24 / 50 1. A long horizontal wire carries an electric current I = 50 A. Point P is located at a distance 2.5 mm above the current. a. What is the direction of the magnetic field at point P? Free Response b. What is the magnitude of the magnetic field at point P? A thin horizontal rod has a length L = 1 and mass m = 50 g is connected to a circuit. The circuit contains a battery V = 12 V, a resistor R = 0.06 Ω, a switch, and connecting wires. The rod is supported in horizontal position by two light connecting wires. c. What is the direction of the electric current in the rod? d. On the diagram show all the applied forces on the rod. e. What is the tension force in supporting wires?
Slide 25 / 50 Slide 26 / 50 1. A long horizontal wire carries an electric current I = 50 A. Point P is located 1. A long horizontal wire carries an electric current I = 50 A. Point P is located at a distance 2.5 mm above the current. at a distance 2.5 mm above the current. a. What is the direction of the magnetic field at point P? b. What is the magnitude of the magnetic field at point P? Out of the page. B = (μ 0 /2π)(I/r) B = (2x10 7 Tm/A)/(50A/0.0025m) B = 0.004T Slide 27 / 50 Slide 28 / 50 1. 1. A thin horizontal rod has a length L = 1 m and mass m = A thin horizontal rod has a length L = 1 m and mass m = 50 g is connected to a circuit. The circuit contains a 50 g is connected to a circuit. The circuit contains a battery V = 12 V, a resistor R = 0.06 Ω, a switch, and battery V = 12 V, a resistor R = 0.06 Ω, a switch, and connecting wires. The rod is supported in horizontal connecting wires. The rod is supported in horizontal position by two light connecting wires. position by two light connecting wires. c. What is the direction of the electric current in the rod? d. On the diagram show all the applied forces on the rod. To the right. F B mg Slide 29 / 50 Slide 30 / 50 2. Charged particle of mass m and charge q is 1. released from rest in region between two charged A thin horizontal rod has a length L = 1 m and mass m = plates M and L. After passing the region of the 50 g is connected to a circuit. The circuit contains a electric field with an accelerating voltage V a the battery V = 12 V, a resistor R = 0.06 Ω, a switch, and particle enters another region filled with a magnetic connecting wires. The rod is supported in horizontal field of magnitude B and directed out of the page. position by two light connecting wires. e. What is the tension force in supporting wires? a. What is the sign of the charge on the particle? ΣF = ma b. What is the velocity of the particle as it enters the magnetic field? T + T - F B - mg = 0 c. What is the direction of the magnetic force on the particle? 2T = F B + mg d. Describe the path of the particle in the magnetic field. T = (F B + mg)/2 T = (I l B + mg)/2 e. What is the radius of the curvature of the particle in the magnetic field? T = [(50A)(1m)(0.004T)+(0.05kg)(9.8m/s 2 )/2 f. What is the direction and magnitude of the electric field that can be used to make the path of the particle straight? T = 0.35N each
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