Karen explains what resistors are, how resistors are represented on a schematic, various types of resistors, and the characteristics of those resistors. She’ll go over carbon composite resistors, thin film resistors such as carbon, metal, and metal oxide film; thick film or cermet resistors; wire round resistors; variable resistors such as thermistors, potentiometers, and photo or LDR resistors; SMD resistors; trimmer pots; and more. According to Ohm’s Law, in every circuit there is a balance between voltage, current, and resistance. Most electrical components require a certain voltage and current to function properly. By adding resistors, you can control the voltage and current in various parts of a circuit. Resistance in an electrical circuit is when a material prevents some or all of the electrical current from flowing through it, converting that restricted energy into heat. Every material has some resistance. In resistors, this principle is used to create a controlled amount of resistance that can be used to regulate circuits. Resistors can be made of a variety of materials. Carbon composite resistors are made by combining a conductive material, usually finely ground carbon or graphite, with a non-conducting material like ceramic. Once widely used, they have mostly been replaced by more efficient and precise resistor types. While cheap to produce, their lack of use means they are often more expensive. Carbon film, metal film, and metal oxide film are examples of thin film resistors. Thin film resistors are generally made by depositing a conductive material onto an insulating ceramic rod or substrate. A laser trimmed pattern is cut into the film in order to increase its conductive or resistive path. The resistance value is controlled by varying the thickness of the film. Thin film resistors are the most common type of through-hole resistors. Surface mount resistors are created using the same method as thin film resistor. Surface mount resistor