Red Seal Electrician Practice
MotorsQuestion 1252 of 1506

What is the rotor frequency at the instant a stopped squirrel cage motor is started?

  1. Zero hertz
  2. Half the line frequency
  3. Double the line frequency
  4. The line frequency
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Correct answer: The line frequency

At rest the slip is 100%, so the field cuts the rotor at the full line frequency. It falls as the rotor speeds up.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 13.7: Tesla Polyphase Induction Motors

Practice motors

Questions last reviewed: 18 October 2026