🔍 Key Concepts

• Behavior of a three-phase rotating magnetic field when line sequence is changed • Difference between changing all three leads vs only two leads in a three-phase system • How direction of rotation is controlled in three-phase induction motors

💭 Think About

• Think about what creates the direction of the rotating magnetic field in a three-phase motor. • Consider what happens to the phase sequence if you swap two of the line connections versus swapping all three. • Ask yourself which components are actually present in a typical squirrel-cage induction motor and which options might apply to other types of AC machines instead.

✅ Before You Answer

• Verify which choice specifically changes the phase sequence of the supply. • Check which listed parts (slip rings, brushes) are commonly found on a standard three-phase induction motor. • Confirm which action would leave the motor running in the same direction because the overall phase order is unchanged.