TPR CBT 5 Question #28 [Magnetism & Torques on Coil]

[sanguinee]

I'm having a very difficult time visualizing this and using the right hand rule because I'm a little confused about which way the velocity goes. Why does the explanation say use the left hand rule & how are we supposed to know electrons are being used even though current is always the direction of positive charges?

I'm getting the right direction of force if I use my right hand rule and say the velocity is moving in the same direction as the current is supposed to be moving (but the explanation reverses the direction of velocity)? Any help would be very much appreciated - thank you!

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[sanguinee]

Also don't understand this question from the passage... why is torque causing sinΘ to decrease?

 

[sanguinee]

Either way, you will get an upward magnetic force on the left coil and a downward magnetic force on the right coil.

Using my right hand rule as the thumb being force, index finger being velocity, and middle finger being the magnetic field, for the RIGHT side [looking from on top], I am pointing my middle finger (magnetic field) away from me because it is going into the paper, index finger points towards the ground, and with this, my thumb (force) points towards the right... What am I doing wrong here that my thumb isn't pointing up? It seems like my right hand rule isn't working at all of this question

Now once the coil starts spinning it will get to a point where the coil is completely perpendicular to the magnetic field, but the magnetic forces will be in the same direction right? So the angle between the magnetic force and the coil is decreasing as the coil spins. And once the angle is 0 there is no more torque since sin 0=0

Do you mean the coil will be completely parallel to the magnetic field? Also, I'm just not understanding what is happening with the coil itself. Why does the coil change angles?? Isn't it just a piece of coil that rotates? Thereafter, how do you know which direction the coil is going in?

Sorry, I am so confused. Thank you for helping @atrain2080