Electricity Knowledge. Study pack. Comprehensive summary notes. rated A+

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Circuit diagrams use standard symbols. Current, Potential Difference and Resistance For electrical charge to flow through a closed circuit the circuit must include a source of potential difference. ... Electric current is a flow of electrical charge. The size of the electric current is the rate of flow of electrical charge. A current has the same value at any point in a single closed loop. The current (I) through a component depends on both the resistance (R) of the component and the potential difference (V) across the component. The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component. The current through an ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor. This means that the resistance remains constant as the current changes. The resistance of components such as lamps, diodes, thermistors and LDRs is not constant; it changes with the current through the component. The resistance of a filament lamp increases as the temperature of the filament increases.The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction. [Show More]

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