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Unformatted text preview: fryer (vdf96) Magnetics 2 graves (6) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Consider a straight wire carrying current I , as shown. R I What is the direction of the magnetic field at point R caused by the current I in the wire? 1. To the right 2. Toward the wire 3. Out of the page correct 4. Into the page 5. To the left 6. Away from the wire Explanation: Use the right-hand rule to determine the direction of the magnetic field surrounding a long, straight wire carring a current (thumb). We find that the magnetic field points Out of the page at point R (fingers). 002 (part 1 of 5) 10.0 points A long, straight wire is in the plane of the page and carries a current of 19 A. Point P is also in the plane of the page and is a perpendicular distance 0 . 8 m from the wire, as shown below. P 19 A . 8 m y z x x is upward from the paper With reference to the coordinate system in the figure above, what is the direction of the magnetic field at point P due to the current in the wire? The permeability of free space is 4 10 7 T m / A. Gravitational effects are negligible. 1. in the negative y direction 2. in the negative x direction correct 3. in the positive z direction 4. in the negative z direction 5. in the positive x direction 6. in the positive y direction Explanation: Using the right hand rule, the magnetic field at point P due to the current in the wire points into the page, or along the negative x-axis; i.e. , hatwide B P = + hatwide x . 003 (part 2 of 5) 10.0 points A 2 . 324 10 26 kg mass particle with nega- tive 1 . 12 10 18 C charge is initially mov- ing parallel to the wire with a 80 m / s speed when it is at point P , as shown below. 80 m / s 2 . 324 10 26 kg 1 . 12 10 18 C 19 A . 8 m y z x x is upward from the paper fryer (vdf96) Magnetics 2 graves (6) 2 With reference to the coordinate system established above, what is the direction of the magnetic force acting on the negative particle at point P ? 1. in the negative x-axis 2. in the positive z-axis correct 3. in the negative y-axis 4. in the negative z-axis 5. in the positive x-axis 6. in the positive y-axis Explanation: The direction of the magnetic force is vector F B = qvectorv vector B P , so hatwide F B = hatwide v hatwide B P = ( hatwide y ) (+ hatwide x ) = + hatwide z . Using the right hand rule, the direction of the magnetic force acting on the negative particle at point P is along the positive z-axis, or upward. 004 (part 3 of 5) 10.0 points Determine the magnitude of the magnetic force acting on the negative particle at point P ....
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