Electromagnetism — finding the current

[physics604]

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.

 

[mfb]

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.

 

[physics604]

That's alright, I finally understand it now.

τ = Fl = 0.20x9.8x0.06 = 0.1176

 

[mfb]

Right.
It would be useful to keep the units everywhere, this gives a direct cross-check for your measurements.

 

[KinzaFatima]

That's alright, I finally understand it now.

τ = Fl = 0.20x9.8x0.06 = 0.1176

Can you please explain me?

 

[Delta2]

Can you please explain me?

he calculates the torque of the mass 0.20g with respect to the central axis of the coil.