How do resistors affect voltage

The best insulators are glasses and ceramics. Plastics, such as epoxy, are generally good insulators. There also are materials that are neither conductors nor insulators. Called "semiconductors," they are used to make transistors. We will not discuss transistors here, but it is interesting that they are really only resistors that electronic circuits can control.

This again shows that Ohms Law is fundamental to circuit design. There are several ways to make resistors for electrical or electronic circuits. Carbon resistors are made by attaching leads to a bar or rod of carbon material. The material is usually made by suspending carbon particles in a plastic material. The material "mix determines resistance. Carbon resistors have some serious limitations. They cannot dissipate much power, and are difficult to make with small resistance tolerances.

However, automated manufacturing makes them in large quantities, so their cost is low. Some resistors are made with metal films or oxides. These resistors are small and can be manufactured with good tolerances. But, they cannot handle higher power levels. Another type of film resistor is made with conductive inks. They are inexpensive, but are unstable and have limited power dissipation and poor resistance tolerances.

Wirewound resistors are made by winding a length of wire on an insulating core. They can dissipate large power levels compared to other types, and can be made with extremely tight resistance tolerances and controlled temperature characteristics.

Its length, cross-section area, and material determine the resistance of a wire. Copper is a good conductor, but has some resistance to current flow. A small diameter copper wire, feet long, may have a resistance of a few ohms. However, a small diameter nickel alloy wire only one foot long may have a resistance of several thousand ohms.

Riedon makes wire wound resistors using wire of several metal alloys and sizes. The selection of wire depends on several factors. For example, a high resistance design would require a long copper wire and the resistor would be large. The same resistor could be made with a short length of nickel alloy wire, resulting in a much smaller device. However, when a high precision resistor is required, it is easier to trim resistance by removing a few inches of a low resistance wire, than by trimming millimeters of high resistance wire.

Next, you squeeze the middle of the hose so that less water flows out. So after the point of the hose where you are squeezing, you know that 0. It must also be 0. You can think of wires as completely filled with electrons at all times. Even when not connected to a battery. When you connect to a battery, the battery starts pushing in electrons. But one electron going in, means that one electron must go out on the other end.

The current that flows out of the plus is exactly the same as the current flowing back into the minus of the battery. The water represents current. The more you squeeze it, the less water can flow. The main way a resistor reduces current is through its physical construction and the materials used internally.

There are many different types of resistors available each being constructed a certain way. Below are some common resistor types:. Inside this resistor is a solid cylindrical resistive element which is a mixture of finely powdered carbon and an insulating material. Increasing the mixture of carbon reduces the resistance, as carbon is a good conductor. These disks are compacted inside the body of the resistor between two metal plates.

Carbon film — A carbon film is placed on an insulating material with a helix cut into it to create a long, narrow path that will reduce current. Varying the shape and size will provide a range of resistance values. Metal film — Many through hole resistors are made of a metal-film. They are coated with nickel chromium NiCr. Metal oxide — These types of resistors are made of metal oxides, which allows the resistor to withstand much higher temperatures.

Wire wound — This resistor reduces current by using a metal wire wound into a coil. The metal used is usually nichrome wound around a ceramic, plastic or fiberglass core.

Without getting into too much detail, he discovered that the amount of electrical charge through a metal conductor in a circuit was directly proportional to the voltage across it, which can be summarised by the equation seen below. An increase in a resistors value will see a decrease in current thereby reducing it, while a decrease in resistance will cause an increase in current.

There are a couple common ways that a resistor can reduce voltage which include a voltage drop across its terminals, and a voltage divider. In the field of electronics, voltage drop occurs in every component that has a resistance. Here the Lamp has a resistance of 10 ohms due to the fact that everything in a circuit has some form of resistance.

So, this current of 1. If we take the current 1. Now we know how to calculate voltage drop, we can take a look how this theory is applied to a resistor to reduce voltage. If we replace the above lamp with a resistor of equivalent resistance 10 ohms we are still going to get the same value of voltage dropped across it.

Now, we will add a second resistor R2 with a resistance of 5 ohms in series with the 10 ohm resistor R1. Just as with the lamp example, we need to find the value of the current flowing through the circuit. This current is the same current that passes through both resistors.