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  Item Reference: KCLCAL-1893-1894-868

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cl FACULTY OF SCIENCE XIII Electrical 1gt1uermg Describe the 44Thomson Double Bridgeמ method for the determination of very small resistances and prove the formula you would employ Point out the advantages of this method over the ordinary Wheatstone Bridge when small resistances have to be measured Discuss the relative advantages and disadvantages of the 44two-wire" and 44three-wire" systems of distribution and describe the different systems of electric light under- ground conductors used in central station work How would you make an efficient vulcanised joint in an electric light cable Γ You have to compound direct current generator in order that it may give an increase of per cent in the volts at its terminals between open circuit and full load and you are limited with regard to rise in temperature of the machine on six hours run Show how you would do this and the precautions you would take The following is diagram of connections for an effici- ency test of two dynamo-electric machines of equal size Their axles are coupled together and the power-difference is supplied by battery The motor magnets are separately excited and the generator excites itself Show precisely the measurements you would make and how you would accu- rately obtain the efficiency of each of the machines in question If you had to design magnetic circuit for dynamo- electric machine in which wrought iron and cast iron are placed side by side in 44parallel" how would you treat the matter priori from knowledge of the dimensions of the parts and the induction curves in order to get at the charac-
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