A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohms. The value of resistance which must be added to obtain rated torque at 1000 rpm is _______ ohms

A 240 V dc series motor takes 40 A when giving its rated output at 150

1.	A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohms. The value of resistance which must be added to obtain rated torque at 1000 rpm is _______ ohms
A.	1.9 ohms
B.	19 ohms
C.	4.2 ohms
D.	None of the above
Answer» B. 19 ohms

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A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohms. The value of resistance which must be added to obtain rated torque at 1000 rpm is _______ ohms

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