Question
What is the principle behind the working of a
transformer? ÂSolution
A transformer works on Faraday's law of induction.  It uses electromagnetic induction to change the voltage in alternating current (AC) circuits.  A varying current in the primary coil induces a varying magnetic field, which in turn induces a current in the secondary coil.  This allows voltage to be increased or decreased.
A train crosses a pole and a platform of length 576 metres in 12 seconds and 30 seconds, respectively. Find the length of train.
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