Electric circuits

• There are two types of current: direct and alternating.
• Electrical charge and current are related concepts in electricity.
• Potential difference and resistance are related concepts in electricity.
• Series circuits and parallel circuits are related concepts in electricity.
• Electrical component A device in an electric circuit, such as a battery, switch or lamp that can be found in an electrical circuit.
• Components Some of the more common components are: Switch A switch used to turn a circuit on (closed) and off (open).
• Lamp An electrical current close current Moving electric charges, eg electrons moving through a metal wire.
• Filament A thin, high resistance wire that gets hot and glows when a current flows through it causing it to emit heat and light.
• Filaments are used in some types of bulb and electrical heaters.
• Fixed resistor A resistor restricts or limits the flow of electrical current.
• Electrical component with a resistance that is fixed and cannot be changed.
• Resistance is measured in ohms.
• Variable resistor Moving the position of the slider on this resistor, changes the resistance.
• A variable resistor close variable resistor A resistor where the value of the resistance can be changed.
• Thermistor The resistance of a thermistor depends on its temperature.
• At low temperatures, the thermistor has a high resistance.
• As the temperature increases, the resistance decreases.
• A thermistor close thermistor An electrical device whose resistance decreases as its temperature increases.
• Light-dependent resistor (LDR) The resistance of a LDR depends on light intensity.
• At low light levels, the LDR has a high resistance.
• As the light intensity increases, the resistance decreases.
• A LDR close LDR A Light Dependent Resistor is a type of resistor which is affected by changes in light levels.
• A cadmium sulphide layer causes a decrease in resistance in the light and increase in the dark.
• Semiconductor diode An electrical device that allows current to flow in one direction only.
• Insulating material doped with impurities to affect electron energy bands and therefore affect conduction properties.
• Diodes are used to convert an alternating current into a direct current.
• Direct current is the movement of charge through a conductor in one direction only.