Domestic electricity and power

• Define electrical power as the rate of energy transfer per second, measured in watts.
• Calculate power utilizing the relationship between energy transferred and time taken.

$P = \frac{E}{t}$

• Explain the relationship between a device's power transfer, the potential difference across it, and the current flowing through it.
• Calculate electrical power using equations relating to current, potential difference, and resistance.

$P = I \times V$

$P = I^2 \times R$

• Describe the energy transformation pathways in various domestic appliances, from battery or mains sources to motors and heating elements.
• Contrast the properties and behaviors of direct voltage against alternating voltage.
• Define direct current (d.c.) as unidirectional charge movement and identify cells and batteries as primary d.c. sources.
• Define alternating current (a.c.) as the continuous directional reversal of charge movement.
• Recall the standard specifications of the UK domestic mains supply as an alternating current with a frequency of $50 \text{ Hz}$ and a voltage of approximately $230 \text{ V}$.
• Explain the distinct roles and functions of the live and neutral wires in a mains electricity input.
• Explain the critical safety functions of the earth wire, fuses, and circuit breakers in preventing electrical hazards.
• Understand the safety rationale for exclusively placing switches and fuses on the live wire within domestic circuits.
• Recall the standard potential differences maintained between the live, neutral, and earth wires in a mains supply.
• Analyze the severe hazards associated with establishing any accidental connection between the live wire and earth.
• Evaluate the relationship between the assigned power ratings of domestic appliances and the corresponding changes in stored energy during their operation.