🔍 Key Concepts

• Synchronous speed of an AC induction motor and how it depends on frequency and number of poles • Meaning of slip (%) and how it relates actual rotor speed to synchronous speed • Unit conversion between revolutions per minute (RPM) and cycles per second (Hz)

💭 Think About

• First, find the synchronous speed of a 4-pole motor on a 60 Hz system using the standard formula, then think about how slip changes that value. • Ask yourself: if slip is 3%, is the actual rotor speed a little lower or a lot lower than synchronous speed? By about how many RPM? • Compare your calculated rotor speed to the choices and see which one is closest while still being slightly less than the synchronous speed.

✅ Before You Answer

• Use the correct synchronous speed formula for induction motors: verify poles and frequency are in the right places in the formula. • Be sure to convert slip from percent to a decimal before using it in any multiplication. • After you calculate rotor speed, confirm it is slightly less than synchronous speed, not more.