Final answer:
The induction motor is being assessed based on its electrical behavior under various loads and circumstances, such as facing a mechanical load or running with no load at all, focusing on the equilibrium between back electromotive force and driving electromotive force.
Step-by-step explanation:
When a high-speed rotor slows down within 1 minute, typically the induction motor is being categorized based on its behavior upon powering up and under mechanical loads. An induction motor experiences higher current draw when it starts than during normal operation. When a mechanical load is applied, such as in the case of an electric wheelchair climbing a hill, the motor may slow down, causing the back electromotive force (emf) to drop. Consequently, there is an increase in current flow, enabling the motor to perform more work. However, if the motor's speed is too low, this higher current can cause overheating due to resistive power in its coils (P = I² R), potentially leading to motor damage. If there is no mechanical load, the motor's angular velocity increases until the back emf almost equals the driving emf, balancing the energy used to mainly overcome friction.