Torque in AC Machines: Why is Theta Same?

AI Thread Summary
The discussion centers on the concept of torque in AC machines, specifically questioning why the angle theta remains the same in two torque equations. It highlights that in the equation torque = Fr sin(theta), theta is typically 90 degrees for DC and synchronous motors, as the net force acts tangentially to the rotor. The confusion arises from the application of theta in different contexts, with the second equation involving magnetic fields. The participant emphasizes the importance of understanding the directional forces involved in torque generation. Overall, the discussion seeks clarity on the consistency of theta in torque calculations across different motor types.
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hi

i have question related to

torque = force X r = Fr sin (theta)
and
torque = k (Br X Bs) = k BsBr sin (theta)

why does theta the same in both ??
 
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theta is not same in both.because in t=frsin(theta) theta will be 90 degrees considering normal dc motors or synchronous motors.because,net force acts in direction in which rotation is possible,that means only along the tangential direction to the rotoe cylinderical body.
 

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