A universal motor runs at 6000 rpm on no-load and 4000 rpm on full-load. Speed regulation is:

Option 1: 0.25

Option 2: 0.333

Option 3: 0.4

Option 4: 0.5

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Correct Option: 4

Explanation

Speed regulation = (N₀ − Nf)/Nf × 100 = (6000 − 4000)/4000 × 100 = 50%.