Electromagnetism — finding the current

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Homework Help Overview

The discussion revolves around a physics problem involving a square coil placed in a magnetic field, where a mass is suspended from the coil. The goal is to determine the current required for the coil to remain horizontal, considering the forces and torques acting on it.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between torque and force, with one participant attempting to calculate torque using the mass and its distance from the axis. Questions arise regarding the necessary current and how to find it without knowing the torque initially.

Discussion Status

The conversation has progressed with some participants clarifying their understanding of torque calculations related to the mass. There is an acknowledgment of the need to maintain unit consistency for verification. However, no consensus has been reached on the final current value needed.

Contextual Notes

Participants are working within the constraints of the problem, which includes specific values for the magnetic field, dimensions of the coil, and the mass. There is an emphasis on understanding the forces and torques involved without providing a complete solution.

physics604
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1. A 35 loop square coil 0.12 m on a side is positioned in a 0.050 T magnetic field. A 0.20 kg
mass is suspended from one side of the coil as shown in the diagram attached. How much current must pass through the coil in order for the coil to remain horizontal?

A. 2.3 A
B. 4.7 A
C. 9.3 A
D. 330 A

Homework Equations



τ=BAIN
F=IlB

The Attempt at a Solution



τ=BAIN
so I=τ/BAN

I know that BAN is 0.050 x 0.122 x 35 (the information is given). However, I'm having a little trouble finding τ (torque).

I know that I need to find the forces on the square coil. But since I don't know I (current), I won't be able to find the force with the equation.

Any help would be greatly appreciated.
 

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The required force is given by the mass. Which torque do you get from the mass?
The coil has to compensate this with its own torque.
 
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That's alright, I finally understand it now.

τ = Fl = 0.20x9.8x0.06 = 0.1176
 
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Right.
It would be useful to keep the units everywhere, this gives a direct cross-check for your measurements.
 
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physics604 said:
That's alright, I finally understand it now.

τ = Fl = 0.20x9.8x0.06 = 0.1176
Can you please explain me?
 
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KinzaFatima said:
Can you please explain me?
he calculates the torque of the mass 0.20g with respect to the central axis of the coil.
 

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