How It Works: Why High-Current Appliances Cost More

⚙️ How It Works: Why High-Current Appliances Cost More

Power in an electrical circuit represents the rate of energy transfer — how many joules of electrical energy are converted into other forms (heat, light, sound, kinetic) every second.

The equation P = I²R reveals something important: power increases with the square of the current. Doubling the current quadruples the power dissipated as heat in a resistor. This is why:

• High-current appliances (showers, kettles) are very expensive to run
• National Grid transmits electricity at very high voltage and low current to minimise energy losses in cables (P = I²R — lower I = far less heating loss)
• Fuses are rated by current — too much current means dangerous overheating

The equation P = V²/R shows that at a fixed voltage (like mains 230 V), lower resistance means more power. This is why a kettle (low resistance heating element) is much more powerful than an LED bulb (high resistance).