🔍 Key Concepts

• Relationship between synchronous speed, frequency, and number of poles in an AC induction motor • How the rotor of a squirrel-cage motor follows the rotating magnetic field of the stator • Which motor parts actually set the speed versus which only affect torque/efficiency

💭 Think About

• Ask yourself: In an AC induction motor, what formula links motor speed to the power supply and machine construction? Which term in that formula can be changed by design? • Consider which option(s) affect the rotating magnetic field speed, and which only influence current, torque, or heating in the rotor. • Think: Does the rotor decide how fast the field turns, or does the stator and line frequency decide that?

✅ Before You Answer

• Recall the formula for synchronous speed in RPM and identify which variable is part of that equation. • Verify which of the listed choices is directly tied to the stator magnetic field pattern (not rotor heating or losses). • Eliminate any options that mainly change resistance or size but do not change the frequency or number of magnetic poles.