Physics paper 1

Current is a flow of electric charge that flows if there is a source of potential difference. 

The greater the resistance across a component, the smaller the current that flows (for a given potential difference across the component).

Charge flow = current x time

Potential difference = current x resistance

Ohmic conductors have a constant resistance. A filament lamp increases in reistance as the temperature increases. So as the current increases, the lamp heats up to cause more resistance. Diodes only let the current one in one direction and have a high resistance in the other direction.

An LDR has high reistance in darkness and lower resistance in bright light.

A thermistor depends on temperature. In hot conditions, the reistance drops and in cool consitions, the resistance goes up.

In series circuits, potential difference is shared, current is the same everywhere, and…