coz in a step up transformer the voltage is increased and the and the current is decreased and vice-versa . and the ohm's law states that voltage is directly propotional to the current .now in a transformer we r making the current inversly propotional to the voltage
A transformer does not make the current inversely proportional to the voltage; the currents in the two coils are inversely proportional to the turns ratio Q. If the secondary (output) coil drives a resistance, the current depends on Ohm's law; Is Vs/R. The resistance equals the ratio Vs/Is. But the ratio V/I in the primary (Vp/Ip) is multiplied by Q^2; that is, V is proportional to Q and I is proportional to 1/Q. So the power source driving the primary sees a load resistance Q^2R. The power, or product of V*I, is the same in the primary and secondary. But no matter what you do with the input voltage, the currents in both windings change proportionally to voltage. You can think of a transformer as similar to a lever, where V and I correspond to F and d (distance), F/d correwponds to R, and Q corresponds to the applied-work and output-work lever lengths. Work Fd is constant on both ends of the lever, and F/d has a Q^2 relationship between the two lengths of the lever.
Transformers don't need electricity to run!
