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sleeppotato
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Ok, so I'm doing an experimental write up for an experiment on adjusting voltage on the speed of a simple DC motor, and changing the number of coils.
I thought that I understood what I was saying but I've recently become a little confused with the concepts of torque vs speed specifically when trying to talk about a torque/speed graph.
I know that as torque increases, speed decreases, but I've also been talking about EMF and Faraday's law todo with how as the motor increases in speed the current drops until the torque is quite small (Due to the equation τ=BAIN cosθ, τ=torque, B = magnetic field, A = area of coil, I = current, N = number of turns) and then the forces are equal as the small torque remaining is balanced due to friction, and also the magnetic field working against the motor that has been produced as it cuts the magnetic field (this is faradays law correct?)
So what I'm not sure about is, do I say that as the number of coils increases, the torque increases (due to the A and N in the above equation) and as such the speed is reduced, or Is it more technically that as the number of coils increases, the generated back emf is larger, and also the magnetic field produced by this back emf is larger, which also causes it to be slowed.
Sorry if this does not make sense.. the motor we used is similar to this: http://www.miniscience.com/projects/Magnet_Motor_kit/Magnet_Motor_LL.jpg
I thought that I understood what I was saying but I've recently become a little confused with the concepts of torque vs speed specifically when trying to talk about a torque/speed graph.
I know that as torque increases, speed decreases, but I've also been talking about EMF and Faraday's law todo with how as the motor increases in speed the current drops until the torque is quite small (Due to the equation τ=BAIN cosθ, τ=torque, B = magnetic field, A = area of coil, I = current, N = number of turns) and then the forces are equal as the small torque remaining is balanced due to friction, and also the magnetic field working against the motor that has been produced as it cuts the magnetic field (this is faradays law correct?)
The Attempt at a Solution
So what I'm not sure about is, do I say that as the number of coils increases, the torque increases (due to the A and N in the above equation) and as such the speed is reduced, or Is it more technically that as the number of coils increases, the generated back emf is larger, and also the magnetic field produced by this back emf is larger, which also causes it to be slowed.
Sorry if this does not make sense.. the motor we used is similar to this: http://www.miniscience.com/projects/Magnet_Motor_kit/Magnet_Motor_LL.jpg