Finding the Magnetic force on the coil

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SUMMARY

The discussion focuses on calculating the magnetic force on a coil using the principles of electromagnetism. The user integrates the force components over a complete revolution, applying the formulae for the horizontal and vertical components of the force, specifically using the equations Fx = ∫0^2π IRBsin(30)dθ and Fy = ∫0^2π IRBcos(30)dθ. The final result for the vertical component, accounting for N turns, is expressed as -π NIRB√3 = -0.443 ĵ N. The approach is validated by peers, confirming the correctness of the calculations and the direction of the forces involved.

PREREQUISITES
  • Understanding of electromagnetism principles, specifically the Lorentz force law.
  • Familiarity with calculus, particularly integration techniques.
  • Knowledge of vector components and their resolution in physics.
  • Experience with magnetic fields and their interaction with current-carrying conductors.
NEXT STEPS
  • Study the Lorentz force law in detail to understand the relationship between current, magnetic fields, and force.
  • Explore advanced integration techniques in calculus to handle complex physical scenarios.
  • Learn about the behavior of magnetic fields around coils and solenoids for practical applications.
  • Investigate the effects of multiple turns in coils on magnetic force calculations.
USEFUL FOR

Students and professionals in physics, electrical engineering, and anyone involved in designing or analyzing electromagnetic systems, particularly those working with coils and magnetic forces.

Physicslearner500039
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Homework Statement
A voice coil in a loudspeaker has 50 turns of wire and a diameter of 1.56 cm, and the current in the coil is 0.950 A. Assume that the magnetic field at each point of the coil has a constant magnitude of 0.220 T and is directed at an angle of 60.0 Deg outward from the normal to the plane of the coil. Let the axis of the coil be in the y-direction. The current in the coil is in the direction shown (counterclockwise as viewed from a point above the coil on the y-axis). Calculate the magnitude and direction of the net magnetic force on the coil.
Relevant Equations
F=ILBSin(Θ)
1598025773773.png

Surely a tough one, I am doing it from the basics. This is the diagram i tried to draw showing the Force and current I
1598027435817.png


The Length L is the tangent to the circle. The Force F is pointing upwards at ##90 Deg## to the ##\vec B## and also perpendicular to ##\vec L##. I am considering a small length ##\vec dL = r d\theta##. Resolving the force into X and Y components and integrating over the complete ##2\pi##.

##Fx = \int_0^{2\pi} IRB\sin(30) d\theta ##
##Fy = \int_0^{2\pi} IRB\cos(30)d\theta ##

Is my approach correct or completely wrong? Please advise
 
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Check the direction of F in your drawing. The current is going into the page at the point where you draw F.

If you consider the forces on diametrically opposite elements of current, what happens when you add their horizontal components?

Your integral for ##F_y## looks good except for maybe the overall sign. If ##\theta## varies from 0 to ##2 \pi##, how many times do you go around the cylinder?
 
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TSny said:
Check the direction of F in your drawing. The current is going into the page at the point where you draw F.
I am not sure how i have done that mistake, the updated diagram is
1598076875045.png

The horizontal components cancel out. The vertical component is for N turns
##-\int_0^{2\pi} NIRB\cos(30)d\theta##
##-\pi NIRB\sqrt3 = -0.443 \hat j N##
 
Looks right to me.
 
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