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A DC cumulative compound motor has a varying load upon it which requires a variation in...

A DC cumulative compound motor has a varying load upon it which requires a variation in armature current from 50 A to 100 A. If the series-field current causes the air-gap flux to change by 4 percent for each 10 A of armature current, find the ratio of torques developed for the two values of armature current?

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