🔍 Key Concepts

• Squirrel-cage induction motor slip and synchronous speed relationship • How changing the number of poles in the stator affects synchronous speed at a fixed frequency • Difference between stator circuit changes (poles / connections) and simply adding resistance

💭 Think About

• At constant supply frequency, what basic motor property determines the no-load (synchronous) speed? • Which of the options would actually change that basic property instead of just wasting power or affecting torque and current? • Think about how multi-speed motors are built internally: what do manufacturers reconfigure to get distinct, fixed speeds?

✅ Before You Answer

• Verify which method will directly change synchronous speed when frequency is fixed. • Check which options are common in practical multi-speed induction motor design versus mainly used for starting or control. • Eliminate any option that only increases losses or affects torque without creating a new, well-defined operating speed.