38) A 10 kVA transformer is taking a power of 400 watts in open circuit test and 900 watts in short circuit test. What will be the copper loss at 50% of load ?

39) What will be the copper loss at half load, of the full load copper loss in 1600 watts ?

40) The wattmeter reading of transformer on open circuit test is 900 W and on short circuit test at full load current is 1600 W. What will be the iron loss at half full load ?

41) The copper loss of the transformer during the maximum efficiency is 1000 watts, what will be the Iron loss ?

42) The efficiency of a transformer is at a maximum value, when the