2/25/2014 Master Ithttp://www.webassign.net/v4cgi/questions/tutorial_popup.tpl 1/2Master ItA rectangular coil consists of N = 115 closely wrapped turns and has dimensions a = 0.400 m and b = 0.300 m. The coil is hinged along the y axis,and its plane makes an angle θ = 30.0° with the x axis (see figure below).(a) What is the magnitude of the torque exerted on the coil by a uniform magnetic field B = 0.605 T directed in the positive x direction whenthe current is I = 1.20 A in the direction shown?(b) If you are looking downward from the positive y direction, what is the expected direction of rotation of the coil?Part 1 of 4 ConceptualizeA magnetic field exerts a torque on a compass needle tending to align it with the field. This is an example of the physics of that phenomenon since acurrentcarrying coil has a magnetic field similar to that of a bar magnet.Part 2 of 4 CategorizeWe use the equations for the torque produced on a loop of current in a magnetic field.Part 3 of 4 AnalyzeThe magnetic moment of the coil is μ = NIA, perpendicular to the plane of the coil, making an angle with the x axis as shown in thediagram. The direction of the vector is along the x axis.(a) The torque on the dipole is given by the cross productpointing down in the diagram, and having a magnitudewhere A is the area of the rectangle, N is the number of coils in the rectangular loop, B is the magnitude of the magnetic field, I is the current, and is the angle between the magnetic moment and the magnetic field Substituting the given values, we have = 60°B = × ,τ μ Bτ = NBAI sin ,μ .Bτ = 1 115 Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. 1Your response differs from the correct answer by more than 10%. Double check your calculations. T 1 0.12 Your response differs from the correct answer by more than 100%. m2 1 1.2 Your response differs from the correct answer by more than 10%. Double check your calculations. A sin 60° = 1 8.68 Your response differs from the correct answer by more than 10%. Double check your calculations. N · m.2/25/2014 Master Ithttp://www.webassign.net/v4cgi/questions/tutorial_popup.tpl 2/2Part 4 of 4 Analyze(b) We model the coil as a rigid body under a net torque;; the coil will rotate so that its magnetic moment is aligned with the magnetic field. Lookingdown from a position on the positive y axis, we see the coil rotate in the -‐‑-‐‑-‐‑Select-‐‑-‐‑-‐‑ clockwise
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