Ch 26: Magnetic Fields and ForcesWorksheetSee all chapters
All Chapters
Ch 01: Units & Vectors
Ch 02: 1D Motion (Kinematics)
Ch 03: 2D Motion (Projectile Motion)
Ch 04: Intro to Forces (Dynamics)
Ch 05: Friction, Inclines, Systems
Ch 06: Centripetal Forces & Gravitation
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Ch 08: Conservation of Energy
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Ch 12: Torque & Rotational Dynamics
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Ch 20: The First Law of Thermodynamics
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Ch 24: Capacitors & Dielectrics
Ch 25: Resistors & DC Circuits
Ch 26: Magnetic Fields and Forces
Ch 27: Sources of Magnetic Field
Ch 28: Induction and Inductance
Ch 29: Alternating Current
Ch 30: Electromagnetic Waves
Ch 31: Geometric Optics
Ch 32: Wave Optics
Ch 34: Special Relativity
Ch 35: Particle-Wave Duality
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Ch 37: Nuclear Physics
Ch 38: Quantum Mechanics

Concept #1: Force and Torque on Current Loops

Example #1: Torque on a Loop at an Angle

Additional Problems
A rigid, rectangular loop, which measures 0.30 m x 0.40 m, carries a current of 7.7 A, as shown. A uniform external magnetic field of magnitude 2.6 T in the negative x-direction is present. Segment CD is in the xz-plane and forms a 33° angle with the z-axis, as shown. The magnetic moment of the loop is closest to? A) 0.31 Am2 B) 0.77 Am2  C) 0.46 Am2 ​ D) 0.62 Am2 ​ E) 0.92 Am2 ​
A circular coil of wire 10.0 cm in diameter has 20 turns and carries a current of I = 10.0 A. The coil is in a region where the magnetic field is B = 0.25 T. What orientation of the coil gives the maximum torque on the coil?
A solenoid with N = 16 turns, length L = 0.30 m, and cross-sectional area  A = 2.0 x 10 -3 m2 sits at an angle Φ = 30° with respect to a uniform magnetic field of magnitude  B = 2.0 x 10-4 T, as shown in the figure. The solenoid carries a current  I and experiences a torque of magnitude 6.4 x 10-9 N•m. What is the magnitude of I? (a) 1.2 mA (b) 0.6 mA (c) 32 mA (d) 2.0 mA (e) 0.5 A (f) none of the above
A square wire 2.0 cm on each side is oriented so that a 5.00 mT magnetic field makes a 30.0° angle with the normal to the plane of the square. If a 1.0 mA current causes a 30.0 Nm torque on the wire, how many loops does the wire make? A) 4.2 x 1010 B) 1.5 x 1010 C) 3.0 x 106 D) 3.0 x 1010
The coil in the figure below lies in the y-z plane, has a current, I, in the direction shown and is free to rotate about the z-axis. What should the direction of an external B-field be to cause a clock-wise rotation as shown? A. Positive y-direction B. Negative y-direction C. Positive z-direction D. Negative z-direction E. Negative x-direction
A copper wire is 8.0 m long and has a cross-sectional area of 1 x 10  -4 m2. The wire forms a loop in the shape of a square and is connected to a battery that applies a potential difference of 10 V such that current flows clockwise (looking down along z-axis) as shown below. The loop is placed on the XY plane in a uniform magnetic field of magnitude 0.5 T directed along the X direction (battery not shown). What is the magnitude of the torque on the loop and its expected direction of rotation? Resistivity of copper is 1.7 x 10-8 Ωm. A. 14706 N.m, rotate about y axis B. 14706 N.m, rotate about z axis C. 24802 N.m rotate about y axis D. 24802 N.m rotate about z axis E. None of the above
An electric current runs through a coil of wire as shown. A permanent magnet is located to the right of the coil. The magnet is free to rotate. What will happen to the magnet if its original orientation is as shown in the figure, with the current coming in on the front side of the solenoid, and then looping around the back? 1. rotate clockwise 2. remain still 3. rotate counterclockwise 4. Unable to determine