16.The efficiency of a machine should be as ______ as possible to reduce the operating cost.

17.The mcrease in heat dissipation by air blasts is due to increase in

18.________ has a lowrelative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable.

19.The change in flux linkages can be caused in which ofthe following ways ?

20.Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as