निम्नलिखित में से कौन सा एक आवरण (covering) के रूप में कार्य करता है जो इंडक्शन मोटर के सभी आंतरिक भागों को सुरक्षा औरंत्रिक शक्ति (mechanical strength) प्रदान करता है?

In a three-phase alternator, the factor that accounts for the reduction in induced EMF because the coils within a phase group are spread across several slots per pole is known as the ________.

Which factor is least significant in determining the rating of a distribution transformer?