Electrical Machines
For a 3-phase, 4 pole, 50 Hz synchronous motor the frequency, pole number and the frequency are halved. The motor speed will be

 3000 rpm
 1500 rpm
 375 rpm
 75 rpm

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Electrical Machines
Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then

 The magnitude of current will decrease but the power factor will increase.
 The magnitude of circuit as well as the power factor will decrease.
 The magnetude of current will increase, but power factor will decrease.
 The magnitude will both increase.

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