A resistor limits the electrical current that flows through a circuit. Resistance is the restriction of current. In a resistor the energy of the electrons that pass through the resistor are changed to heat and/or light. For example, in a light bulb there is a resistor made of tungsten which converts the electrons into light.
Series and parallel
Resistors can be linked in various combinations to help make a circuit:
- Series – Where the resistors are linked one after another.
- Parallel – Where the resistors are linked over one another.
There are many different types of resistors. Resistors have different ratings to tell electricians how much power they can handle before they break and how accurately they can slow the flow of electricity. Connecting two resistors in series results in a higher resistance than when you connect the same two resistors in parallel. To prevent the resistor from reaching its capacity, place the resistors in parallel to keep the total resistance lower. Nowadays the electrical industry in many cases uses so called surface-mount technology based resistors which can be very small.
An inductor is an electrical device used in electrical circuits because of magnetic charge.
An inductor is usually made from a coil of conducting material, like copper wire, that is then wrapped around a core made from either air or a magnetic metal. If you use a more magnetic material as the core, you can get the magnetic field around the inductor to be pushed in towards the inductor, giving it better inductance. Small inductors can also be put onto integrated circuits using the same ways that are used to make transistors. Aluminum is usually used as the conducting material in this case.
How inductors are used
Inductors are used often in analog circuits. Two or more inductors that have coupled magnetic flux make a transformer. Transformers are used in every power grid around the world.
Inductors are also used in electrical transmission systems, where they are used to lower the amount of voltage an electrical device gives off or lower the fault current. Because inductors are heavier than other electrical components, people have been using them in electrical equipment less often.
Inductors with an iron core are used for audio equipment, power conditioning, inverter systems, rapid transit and industrial power supplies.