henry chow wrote: (snip)
You apply voltage across the primary, and the transformer passes as much current as it passes. In the above example, the primary current would be 2 amps only if the secondary load current were 1 amp and it was an ideal transformer (no losses, perfect magnetic coupling between the windings, and no magnetizing current).
If the transformer were large enough to supply that current without sagging its output voltage.
There is no contradiction because there is no way to specify the primary current and the primary voltage, independent of the secondary load. You can control the primary current to be 2 amps, but that requires you to change the primary voltage to whatever produces that 2 amp current. If you did that, with the 50 ohm resistor connected to the secondary, the resistor current would be 1 amp, but that is because the secondary voltage would have to have fallen to 50 volts, which means that the only way the primary current could be 2 amps under these conditions would be if you lowered the primary voltage to
25 volts. Then, the voltage and current ratios would remain consistent.I hope I have.
It falls to 0.5 amp, and the primary current falls to 1 amp. The load resistor reflects back through the transformer to the primary voltage.