Electrical power and the National Grid

The idea

Power P = VI = I²R. Energy transferred E = Pt = QV. Appliances transfer energy from the mains to the motors and heating devices. The National Grid connects power stations to consumers: step-up transformers increase the potential difference and reduce the current for transmission, which reduces energy lost as heat in the cables, making it efficient. Step-down transformers reduce the potential difference for safe domestic use.

1. Pick P = VI, P = I²R, E = Pt or E = QV.
2. Use watts, amps, volts, ohms, seconds and joules.
3. Link high voltage to low current and less heating.

Watch out Use E = Pt with time in seconds and power in watts to get joules.