Originally Posted by

**rcmango** A step-down transformer (turns ratio = 1:8) is used with an electric train to reduce the voltage from the wall receptacle to a value needed to operate the train. When the train is running, the current in the secondary coil is 1.9 A.

What is the current in the primary coil?

in Amperes

if the formula for current in the secondary coil is: A * (ratio of primary coil/secondary coil) = current

then why can't we just use A* 1/8 = 1.9

multiply by 8 and get the amps for the first coil which is 15.2 A