Final answer:
The motor constant is unrelated to angular speed and is a fixed value, while efficiency can change with angular speed, particularly when the motor is under load or first starts up.
Step-by-step explanation:
The motor constant does not depend on the angular speed. It is a physical constant related to the motor's design, including its magnetic field strength and the number of turns in the coil. It's a measure of the torque the motor produces per unit of current. Efficiency of a motor (η = Vₑₘ / Vₐ), on the other hand, can depend on angular speed. When the motor has no mechanical load, it will reach a speed where the back electromotive force (emf) nearly equals the driving voltage, minimizing current draw and optimizing efficiency. However, at lower speeds under load, higher current draw can lead to resistive losses (P = I² R), which reduce efficiency.
When answering questions related to an electric motor, it's crucial to distinguish between different parameters and their dependencies. For example, when a motor first starts, it will draw more current, which lowers efficiency, and upon reaching its operating speed with no load, the back emf increases, reducing the current and potentially increasing efficiency.