Electrical Machines
When R2 is rotor resistance, X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running condition will be

  R2 = s2X2.
  sR2 = X2.
  R2 = sX2.
  R2 = s2X2.

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Electrical Machines
Two dc machines A and B, using the same conductor material, have armature circuit resistances of 0.4 Ω and 1.2 Ω respectively. Of the two machines,

 A is bigger than B for the same current rating
 both are of the same size for the same current rating
 B is bigger than A for the same current rating
 A is bigger than B for the same voltage rating

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