🔍 Key Concepts

• Synchronous speed of an AC motor and how it depends on frequency and number of poles • The definition of slip in an induction (squirrel‑cage) motor • Converting the slip formula into a percentage

💭 Think About

• First, calculate the motor’s synchronous speed using the given frequency and number of poles. What standard formula relates these? • Next, compare synchronous speed to the given full‑load speed. Is slip based on the difference or the ratio between these speeds? • Once you find slip as a decimal or fraction, how do you convert that to a percentage to match the answer choices?

✅ Before You Answer

• Make sure you are using RPM consistently for both synchronous speed and full‑load speed (no unit mix‑ups). • Verify that your slip formula matches: slip = (Ns − Nr) / Ns, where Ns is synchronous speed and Nr is rotor (actual) speed. • After converting to percent, check if your result is a small percentage (typical for full‑load slip in squirrel‑cage motors).