Electricity Knowledge Organiser

Ever wondered why your phone charger gets warm or how dimmer switches work? Electrical circuits follow predictable patterns that you can master with a few key concepts.

Potential difference (also called voltage) measures the electrical work done by a battery or power supply as charge flows around a circuit. Think of it like water pressure in pipes - the higher the voltage, the more 'push' the electricity has. It's measured in volts (V).

Electric current is the flow of electrical charge around a circuit. The bigger the current, the faster the charge flows. Resistors are components that limit this current flow - high resistance means low current, just like a narrow pipe restricts water flow.

Two crucial relationships exist in circuits. When quantities are directly proportional, doubling one doubles the other (creating a straight line graph through the origin). When they're inversely proportional, doubling one halves the other. Ohmic conductors follow Ohm's law perfectly - their resistance stays constant. Non-ohmic components like filament bulbs change their resistance as current changes, which is why bulbs get brighter gradually when you switch them on.

Quick Tip: Remember that in ohmic conductors, if voltage doubles, current doubles too, but resistance stays the same!

The essential equations you'll need are: P = V × I (power), V = I × R (Ohm's law), Q = I × t (charge), and E = V × Q (energy). These formulas connect all the key electrical quantities and will appear in most exam questions.