Higher: transformer power and transmission

Power is conserved in the ideal model

For a transformer treated as 100% efficient, input electrical power equals output electrical power. Since power = potential difference × current, VpIp = VsIs. A step-up transformer raises potential difference but reduces current for the same power transfer. A step-down transformer lowers potential difference and increases available current. Real transformers dissipate some energy, so their output power is lower than their input power.