Relationship among current, voltage, Torque,speed,coil diameter,coil length of motor and if any of the above changes how other parameters get affected.

Ans) The maximum torque happens at 0 rpm, and is known as stall torque. The minimum torque (zero) happens at maximum rpm, reached when the motor is not under a load, and is therefore called free rpm. The formula for torque at any given rpm is: T = Ts - (N Ts ÷ Nf) where T is the torque at the given rpm N, T s is the stall torque, and N f is the free rpm.